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Rule out the usual hiding places first. If the piece really is gone, check the set piece by piece and leave with the element ID LEGO asks for, or a link to buy the part.

ROBOLAB Team Challenge Set (Serial)

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9790 ROBOLAB Team Challenge Set (Serial)

727 pieces in 140 part and color combinations.

Before you call it missing

Builders who report a missing piece often find it in one of these places. Tick each one off as you look.

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Piece checklist

Bricks 98 pieces

  • Brick 1 x 2 Black Part 3004 Element 300426 ×20
  • Brick 1 x 4 Black Part 3010 Element 301026 ×6
  • Brick 2 x 2 Black Part 3003 Element 4103587 or 300326 ×20
  • Brick 2 x 2 Corner Black Part 2357 Element 235776 or 235726 ×4
  • Brick 2 x 4 Black Part 3001 Element 300126 ×25
  • Brick 2 x 6 Black Part 2456 Element 4181144 or 245626 ×6
  • Brick 2 x 8 Black Part 3007 Element 6037390 or 300726 ×8
  • Brick 1 x 2 Green Part 3004 Element 4107736 or 300428 ×4
  • Brick 2 x 4 Green Part 3001 Element 4106356 or 300128 ×1
  • Brick 1 x 2 Yellow Part 3004 Element 4613966 or 300424 ×4

Technic Pins 96 pieces

  • Technic Pin Long with Friction Ridges Lengthwise, 2 Center Slots Black Part 6558 Element 655826 ×8
  • Technic Pin with Friction Ridges Lengthwise and Center Slots Black Part 2780 Element 4121715 or 278026 ×24
  • Technic Pin 3/4 Dark Gray Part 32002 Element 4109854 ×16
  • Technic Axle Pin without Friction Ridges Lengthwise Light Gray Part 3749 Element 4184168 or 4154179 ×16
  • Technic Pin 1/2 without Friction Ridges Light Gray Part 4274 Element 427402 ×8
  • Technic Pin without Friction Ridges Lengthwise Light Gray Part 3673 Element 4184166 or 367302 ×24

Plates 95 pieces

  • Plate 2 x 2 Blue Part 3022 Element 4613973 or 302223 ×4
  • Plate 2 x 2 Green Part 3022 Element 302228 ×2
  • Plate 2 x 8 Green Part 3034 Element 303428 ×4
  • Plate 1 x 1 Light Gray Part 3024 Element 302402 ×8
  • Plate 1 x 10 Light Gray Part 4477 Element 447702 ×6
  • Plate 1 x 2 Light Gray Part 3023 Element 302302 ×20
  • Plate 1 x 4 Light Gray Part 3710 Element 371002 ×10
  • Plate 1 x 6 Light Gray Part 3666 Element 366602 ×10
  • Plate 1 x 8 Light Gray Part 3460 Element 346002 ×8
  • Plate 2 x 10 Light Gray Part 3832 Element 383202 ×6
  • Plate 2 x 2 Light Gray Part 3022 Element 302202 ×8
  • Plate 6 x 10 Light Gray Part 3033 Element 303302 ×1
  • Plate 1 x 3 Yellow Part 3623 Element 362324 ×2
  • Plate 2 x 4 Yellow Part 3020 Element 302024 ×6

Technic Bricks 72 pieces

  • Technic Brick 1 x 10 [9 Pin Holes] Black Part 2730 Element 273026 ×8
  • Technic Brick 1 x 12 [11 Pin Holes] Black Part 3895 Element 389526 ×6
  • Technic Brick 1 x 16 [15 Pin Holes] Black Part 3703 Element 370326 ×6
  • Technic Brick 1 x 2 [1 Pin Hole] Black Part 3700 Element 370026 ×12
  • Technic Brick 1 x 4 [3 Pin Holes] Black Part 3701 Element 370126 ×10
  • Technic Brick 1 x 6 [5 Pin Holes] Black Part 3894 Element 389426 ×8
  • Technic Brick 1 x 8 [7 Pin Holes] Black Part 3702 Element 370226 ×8
  • Technic Brick 1 x 2 with Axle Hole Type 1 [+ Opening] and Bottom Ridges Green Part 32064c ×8
  • Technic Brick 1 x 4 [3 Pin Holes] Green Part 3701 Element 4107790 ×2
  • Technic Brick 1 x 2 [1 Pin Hole] Yellow Part 3700 Element 370024 ×4

Technic Bushes 56 pieces

  • Technic Bush Light Gray Part 3713 Element 4125313 or 659002 ×40
  • Technic Bush 1/2 Smooth with Axle Hole Reduced Light Gray Part 32123a ×16

Wheels and Tyres 46 pieces

  • Technic Wedge Belt Wheel Tire Black Part 2815 Element 6028041 or 281526 ×2
  • Tread Large, Technic [34 Links] Black Part 71372 Element 4107488 ×2
  • Tyre 30 x 10.5 Offset Tread Black Part 2346 Element 234676 or 234626 ×4
  • Tyre 30.4 x 14 VR Black Part 6578 Element 4561806 or 657826 ×2
  • Tyre 43 x 17 Black Part 3634 Element 4523564 or 363426 ×2
  • Tyre 49.6 x 28 VR Black Part 6594 Element 75778 ×2
  • Tyre 81.6 x 15 Motorcycle Black Part 2902 Element 6226880 or 4562873 ×4
  • Tyre Offset Tread 24 x 8 Black Part 3483 Element 4501048 or 348326 ×2
  • Technic Wedge Belt Wheel [aka Pulley] Light Gray Part 4185 Element 4100502 or 418502 ×4
  • Technic Tread Hub White Part 32007 Element 4107487 ×4
  • Wheel 49.6 x 28 VR (36.8 x 26) with Axle Hole White Part 6595 Element 4496709 or 4179486 ×2
  • Wheel 61.6 x 13.6 Motorcycle White Part 2903 Element 290301 ×4
  • Wheel Rim 24 x 14 VR with Center Axle Hole White Part 2994 Element 4496671 or 299401 ×2
  • Wheel with Split Axle hole Yellow Part 3482 Element 348224 ×10

Technic Gears 39 pieces

  • Technic Worm Gear Black Part 4716 Element 6037533 or 471626 ×4
  • Technic Gear Differential, 24 -16 Tooth with Clutch on Both Sides Dark Gray Part 6573 Element 657327 ×1
  • Technic Gear 12 Tooth Bevel Light Gray Part 6589 Element 658902 ×8
  • Technic Gear 16 Tooth with Round Holes [Old Style] Light Gray Part 4019 Element 4107176 or 401902 ×4
  • Technic Gear 24 Tooth Crown with Reinforcements [New Style] Light Gray Part 3650c Element 365002 ×4
  • Technic Gear 24 Tooth [New Style with Single Axle Hole] Light Gray Part 3648b Element 4107543 or 364802 ×4
  • Technic Gear 40 Tooth Light Gray Part 3649 Element 364902 ×4
  • Technic Gear 8 Tooth Light Gray Part 3647 Element 364702 ×6
  • Technic Gear Rack 1 x 4 Light Gray Part 3743 Element 374302 ×4

Plates Special 34 pieces

  • Plate Special 1 x 1 with Clip Horizontal [Thick U Clip] Black Part 6019 Element 601976 or 601926 ×2
  • Plate Special 1 x 1 with Clip Vertical [Thick U Clip] Black Part 4085c Element 408526 ×2
  • Bracket 2 x 2 - 2 x 2 Light Gray Part 3956 Element 395602 ×4
  • Plate Special 1 x 2 with Door Rail Light Gray Part 32028 Element 4109642 ×8
  • Plate Special 2 x 2 with 2 Pin Holes Light Gray Part 2817 Element 281702 ×2
  • Technic Plate 2 x 4 [3 Holes] Light Gray Part 3709 Element 370902 ×4
  • Technic Plate 2 x 6 [5 Holes] Light Gray Part 32001 Element 3200102 ×4
  • Technic Plate 2 x 8 [7 Holes] Light Gray Part 3738 Element 373802 ×8

Technic Axles 33 pieces

  • Technic Axle 10 Black Part 3737 Element 373726 ×4
  • Technic Axle 12 Black Part 3708 Element 370826 ×2
  • Technic Axle 2 Notched Black Part 32062 Element 4109810 or 3206226 ×8
  • Technic Axle 3 Black Part 4519 Element 6238084 or 451926 ×3
  • Technic Axle 4 Black Part 3705 Element 370526 ×2
  • Technic Axle 6 Black Part 3706 Element 370626 ×6
  • Technic Axle 8 Black Part 3707 Element 370726 ×6
  • Technic Axle 3 with Stud Dark Gray Part 6587 Element 4113884 or 658727 ×2

Bricks Sloped 31 pieces

  • Brick Sloped 45° 2 x 1 with Bottom Pin Black Part 3040b Element 4121966 or 304026 ×12
  • Brick Sloped Inverted 33° 3 x 2, Connections between Studs, Ovoid Bottom Pin Black Part 3747b Element 4500458 or 374726 ×4
  • Brick Sloped Inverted 45° 2 x 1 Black Part 3665 Element 366526 ×4
  • Brick Sloped 45° 2 x 2 Green Part 3039 Element 303928 ×3
  • Brick Sloped 45° 2 x 1 with Bottom Pin Yellow Part 3040b Element 4121965 or 304024 ×4
  • Brick Sloped Inverted 45° 2 x 1 Yellow Part 3665 Element 366524 ×4

Electronics 18 pieces

  • Wire with Brick 2 x 2 x 2/3 Pair, 162L Black Part 5306bc162 Element 75656 ×2
  • Wire with Brick 2 x 2 x 2/3 Pair, 20L Black Part 5306bc020 Element 4100355 ×4
  • Sensor, Light with Fixed Cable Blue Part 2982c01 Element 4119421 ×1
  • Transmitter Tower, IR, Serial with Black Front Dark Gray Part 76091 Element 4121506 ×1
  • Cable, Serial, for IR Transmitter Tower Light Gray Part 71793 Element 4119830 ×1
  • Motor Pulley, 9V Micromotor with axle hole Light Gray Part 2983 Element 298630 ×4
  • Motor, 9V Mini [Old Style] Light Gray Part 71427c01 Element 4107786 ×2
  • Sensor, Touch Light Gray Part 879 Element 4247135 or 4209116 ×2
  • Hub, RCX 1.0, with Power Jack [Complete Assembly] Yellow Part 76048c01 Element 4108028 ×1

Technic Connectors 18 pieces

  • Technic Axle and Pin Connector Angled #1 Blue Part 32013 Element 6332570 or 4107797 ×4
  • Technic Axle 1.5 with Perpendicular Axle Connector (Technic Pole Reverser Handle) Light Gray Part 6553 Element 655302 ×2
  • Technic Axle Connector Ridged [with x Hole x Orientation] Light Gray Part 6538b Element 4113804 or 4100408 ×2
  • Technic Axle Connector with Axle Hole Light Gray Part 32039 Element 4106469 ×2
  • Technic Axle and Pin Connector Angled #5 - 112.5° Light Gray Part 32015 Element 4106378 ×4
  • Technic Axle and Pin Connector Perpendicular Light Gray Part 6536 Element 4173667 or 653602 ×2
  • Technic Axle and Pin Connector Perpendicular 3L with Pin Hole Light Gray Part 32068 Element 4114669 ×2

Hinges, Arms and Turntables 16 pieces

  • Arm Grab Jaw Black Part 4221 Element 422126 ×4
  • Arm Piece with Pin, 2 Fingers Black Part 6048a Element 604826 ×2
  • Hinge Plate 1 x 2 with 3 Fingers [Hollow Studs] Black Part 4275b Element 427526 ×2
  • Hinge Tile 1 x 2 1/2 with 2 Fingers on Top Black Part 4531 Element 453126 ×2
  • Turntable 2 x 2 Plate, Base Blue Part 3680 Element 368023 ×2
  • Turntable 2 x 2 Plate - Top Light Gray Part 3679 Element 367952 or 367902 ×2
  • Arm Grab Jaw Holder, 3 Fingers Yellow Part 4220 Element 4107528 or 422024 ×2

Plates Round Curved and Dishes 14 pieces

  • Plate Round 1 x 1 with Solid Stud Black Part 6141 Element 614126 ×2
  • Plate Round 2 x 2 with Rounded Bottom [Boat Stud] Black Part 2654 Element 4617551 or 4278359 ×2
  • Plate Round 1 x 1 with Solid Stud Blue Part 6141 Element 614123 ×2
  • Plate Round 2 x 2 with Axle Hole Type 1 (+ Opening) Blue Part 4032a Element 403223 ×2
  • Dish 4 x 4 Inverted [Radar] White Part 3960 Element 396001 ×2
  • Plate Round 1 x 1 with Solid Stud White Part 6141 Element 6601919 or 614101 ×2
  • Plate Round 2 x 2 with Axle Hole Type 1 (+ Opening) White Part 4032a Element 6601914 or 403201 ×2

Tubes and Hoses 14 pieces

  • Hose, Ribbed 7mm D. 9L / 7.2cm Black Part 78c09 Element 6443871 or 6420612 ×4
  • Hose, Ribbed 7mm D. 9L / 7.2cm Dark Turquoise Part 78c09 Element 4275293 or 4114737 ×4
  • Hose, Ribbed 7mm D. 12L / 9.6cm Purple Part 78c12 Element 4275294 or 4114738 ×4
  • Hose Rigid 3mm D. 19L / 15.2cm Yellow Part 75c19 Element 4579744 or 4118600 ×2

Bricks Round and Cones 12 pieces

  • Brick Round 2 x 2 with Axle Hole Black Part 3941 Element 614376 or 614326 ×8
  • Cone 1 x 1 [No Top Groove] White Part 4589 Element 458901 ×2
  • Cone 1 x 1 [No Top Groove] Yellow Part 4589 Element 458924 ×2

Technic Beams 12 pieces

  • Technic Beam 1 x 9 Bent (6 - 4) Thick Black Part 6629 Element 6279881 or 4119800 ×2
  • Technic Beam 1 x 3 Thin Light Gray Part 6632 Element 4107825 ×2
  • Technic Beam 1 x 4 Thin with Stud Connector Light Gray Part 2825 Element 4107133 or 282502 ×2
  • Technic Beam 1 x 5 Thin Light Gray Part 32017 Element 4106885 ×2
  • Technic Beam 1 x 11.5 Double Bent Thick Yellow Part 32009 Element 6271150 or 6257104 ×4

String, Bands and Reels 8 pieces

  • Rubber Band Small 13mm (Square Cross Section) Black Part 71509 Element 4141606 or 4107153 ×2
  • Technic Rubber Belt Medium [24mm ID] [Round Cross Section] Blue Part 85544 ×2
  • Rubber Belt Small [15mm ID] [Round Cross Section] White Part 85543 Element 6699001 or 4580665 ×1
  • Technic Rubber Belt Large [33mm ID] [Round Cross Section] Yellow Part 85546 Element 4544151 or 70905 ×3

Bricks Curved 4 pieces

  • Brick Curved 2 x 3 Green Part 6215 Element 621528 ×4

Technic Steering, Suspension and Engine 4 pieces

  • Technic Engine Crankshaft Center Light Gray Part 2854 Element 285402 ×2
  • Technic Steering Pulley Large Light Gray Part 3736 Element 373602 ×2

Animal / Creature Body Parts 2 pieces

  • Creature Body Part, Dragon Wing Trans-Neon Orange Part 6133 Element 4106519 ×2

Plates Wedged 2 pieces

  • Wedge Plate 3 x 6 Cut Corners Green Part 2419 Element 241928 ×2

Technic Special 2 pieces

  • Technic Cam Light Gray Part 6575 Element 657502 ×2

Tools 1 piece

  • Brick Separator v1.0 Dark Gray Part 6007 Element 600727 ×1

Tick each piece as you find it, or mark it missing.

When a piece really is missing

Ask LEGO

LEGO takes requests for pieces missing from a new set through its customer service site. The form asks for the set number and each piece's element ID, the number printed beside the piece in the parts list at the back of the instructions. This checker lists both.

Request a replacement from LEGO

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Mark a piece missing and your list links it to an eBay search for that part, which also covers pieces from older or second-hand sets.

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Copy or download your missing list (the CSV opens in any spreadsheet), or print the whole checklist and tick pieces off on paper. Your marks stay in this browser, so you can check a big set over several sittings.

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