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LEGO Missing Piece Checker

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.

Robotics Discovery Set

Checking

9735 Robotics Discovery Set

390 pieces in 109 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

Technic Pins 55 pieces

  • Technic Pin Long with Friction Ridges Lengthwise, 2 Center Slots Black Part 6558 Element 655826 ×2
  • Technic Pin with Friction Ridges Lengthwise and Center Slots Black Part 2780 Element 4121715 or 278026 ×13
  • Technic Pin 3/4 Dark Gray Part 32002 Element 4109854 ×8
  • Technic Pin Long with Friction Ridges Lengthwise and Stop Bush [3 Lateral Holes, Big Pin Hole] Dark Turquoise Part 32054 Element 4140804 or 4120240 ×8
  • Technic Axle Pin without Friction Ridges Lengthwise Light Gray Part 3749 Element 4184168 or 4154179 ×8
  • Technic Pin 1/2 without Friction Ridges Light Gray Part 4274 Element 427402 ×4
  • Technic Pin without Friction Ridges Lengthwise Light Gray Part 3673 Element 4184166 or 367302 ×12

Plates 42 pieces

  • Plate 1 x 4 Dark Turquoise Part 3710 Element 6350418 or 4121705 ×6
  • Plate 1 x 10 Light Gray Part 4477 Element 447702 ×2
  • Plate 1 x 2 Light Gray Part 3023 Element 302302 ×14
  • Plate 1 x 3 Light Gray Part 3623 Element 362302 ×4
  • Plate 1 x 4 Light Gray Part 3710 Element 371002 ×4
  • Plate 1 x 6 Light Gray Part 3666 Element 366602 ×2
  • Plate 1 x 8 Light Gray Part 3460 Element 346002 ×2
  • Plate 2 x 10 Light Gray Part 3832 Element 383202 ×2
  • Plate 2 x 2 Light Gray Part 3022 Element 302202 ×2
  • Plate 6 x 10 Light Gray Part 3033 Element 303302 ×2
  • Plate 1 x 4 Yellow Part 3710 Element 371024 ×2

Technic Bricks 41 pieces

  • Technic Brick 1 x 1 with Pin Hole Blue Part 6541 Element 4119014 ×4
  • Technic Brick 1 x 10 [9 Pin Holes] Blue Part 2730 Element 273023 ×4
  • Technic Brick 1 x 12 [11 Pin Holes] Blue Part 3895 Element 389523 ×2
  • Technic Brick 1 x 16 [15 Pin Holes] Blue Part 3703 Element 370323 ×6
  • Technic Brick 1 x 2 [1 Pin Hole] Blue Part 3700 Element 370023 ×8
  • Technic Brick 1 x 4 [3 Pin Holes] Blue Part 3701 Element 370123 ×4
  • Technic Brick 1 x 6 [5 Pin Holes] Blue Part 3894 Element 389423 ×8
  • Technic Brick 1 x 8 [7 Pin Holes] Blue Part 3702 Element 370223 ×2
  • Technic Brick 1 x 2 with Axle Hole Type 1 [+ Opening] and Bottom Pin Dark Turquoise Part 32064a Element 4112290 ×2
  • Technic Brick 1 x 2 [2 Pin Holes] Light Gray Part 32000 Element 3200002 ×1

Bricks 30 pieces

  • Brick 1 x 2 Blue Part 3004 Element 4613959 or 300423 ×16
  • Brick 2 x 2 Blue Part 3003 Element 4103589 or 300373 ×2
  • Brick 2 x 4 Blue Part 3001 Element 300173 or 300123 ×10
  • Brick 2 x 6 Blue Part 2456 Element 4181139 or 245623 ×2

Technic Bushes 28 pieces

  • Technic Bush Light Gray Part 3713 Element 4125313 or 659002 ×20
  • Technic Bush 1/2 Smooth with Axle Hole Reduced Light Gray Part 32123a ×8

Technic Connectors 28 pieces

  • Technic Axle and Pin Connector Angled #1 Blue Part 32013 Element 6332570 or 4107797 ×4
  • Technic Axle and Pin Connector Angled #3 - 157.5° Blue Part 32016 Element 6261397 or 6177396 ×4
  • Technic Axle and Pin Connector Angled #6 - 90° Blue Part 32014 Element 4112205 ×2
  • 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 ×4
  • Technic Axle Connector with Axle Hole Light Gray Part 32039 Element 4106469 ×4
  • Technic Axle and Pin Connector Angled #5 - 112.5° Light Gray Part 32015 Element 4106378 ×2
  • Technic Axle and Pin Connector Perpendicular Light Gray Part 6536 Element 4173667 or 653602 ×6

Plates Special 24 pieces

  • Plate Special 1 x 2 with 4 x 4 disk at 90 degrees Blue Part 30209 Element 4114691 ×2
  • Plate Special 1 x 2 with Door Rail Light Gray Part 32028 Element 4109642 ×4
  • 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 ×6
  • Technic Plate 2 x 8 [7 Holes] Light Gray Part 3738 Element 373802 ×6
  • Technic Plate 2 x 4 [3 Holes] Purple Part 3709 Element 4118908 ×2

Technic Axles 20 pieces

  • Technic Axle 10 Black Part 3737 Element 373726 ×2
  • Technic Axle 12 Black Part 3708 Element 370826 ×2
  • Technic Axle 2 Notched Black Part 32062 Element 4109810 or 3206226 ×4
  • Technic Axle 3 Black Part 4519 Element 6238084 or 451926 ×2
  • Technic Axle 4 Black Part 3705 Element 370526 ×2
  • Technic Axle 5 Black Part 32073 Element 4114740 ×2
  • Technic Axle 6 Black Part 3706 Element 370626 ×2
  • Technic Axle 8 Black Part 3707 Element 370726 ×2
  • Technic Axle 3 with Stud Dark Gray Part 6587 Element 4113884 or 658727 ×2

Technic Gears 16 pieces

  • Technic Gear 16 Tooth with Round Holes [Old Style] Light Gray Part 4019 Element 4107176 or 401902 ×2
  • Technic Gear 24 Tooth Crown with Reinforcements [New Style] Light Gray Part 3650c Element 365002 ×2
  • Technic Gear 24 Tooth [New Style with Single Axle Hole] Light Gray Part 3648b Element 4107543 or 364802 ×2
  • Technic Gear 40 Tooth Light Gray Part 3649 Element 364902 ×4
  • Technic Gear 8 Tooth Light Gray Part 3647 Element 364702 ×4
  • Technic Gear 24 Tooth Clutch with Dark Gray or Light Gray Center White Part 76019 Element 4270486 ×2

Plates Round Curved and Dishes 14 pieces

  • 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 ×3
  • Plate Round 1 x 1 with Solid Stud Light Gray Part 6141 Element 614102 ×3
  • Dish 2 x 2 Inverted [Radar] White Part 4740 Element 6601845 or 474001 ×2
  • Dish 4 x 4 Inverted [Radar] White Part 3960 Element 396001 ×2
  • Plate Round 2 x 2 with Axle Hole Type 1 (+ Opening) White Part 4032a Element 6601914 or 403201 ×2

Technic Beams 14 pieces

  • Technic Beam 1 x 9 Bent (6 - 4) Thick Dark Turquoise Part 6629 Element 4114291 or 4112285 ×2
  • Technic Beam 1 x 3 Thin Light Gray Part 6632 Element 4107825 ×4
  • 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 ×4
  • Technic Beam 1 x 11.5 Double Bent Thick Purple Part 32009 Element 4114447 or 4112277 ×2

Bricks Round and Cones 10 pieces

  • Brick Round 2 x 2 with Axle Hole Blue Part 3941 Element 614373 or 614323 ×4
  • Brick Round Corner 4 x 4 Full Brick Blue Part 2577 Element 4240191 or 4193523 ×4
  • Dome Hemisphere 4 x 4 Multifaceted Trans-Neon Green Part 30208 Element 6031104 or 4114690 ×2

Tiles 10 pieces

  • Tile 2 x 2 with Groove Dark Turquoise Part 3068b Element 6273853 or 4112916 ×2
  • Tile 1 x 2 with Groove Light Gray Part 3069b Element 306902 ×2
  • Tile 1 x 4 with Groove Light Gray Part 2431 Element 243102 ×4
  • Tile 1 x 8 with Groove Light Gray Part 4162 Element 416202 ×2

Electronics 9 pieces

  • Wire with Brick 2 x 2 x 2/3 Pair, 20L Black Part 5306bc020 Element 4100355 ×2
  • Wire with Brick 2 x 2 x 2/3 Pair, 36L Black Part 5306bc036 Element 75652 ×2
  • Hub, Scout Brick [Complete Assembly] Blue Part 32104c01 Element 4141010 ×1
  • Motor, 9V Mini [Old Style] Light Gray Part 71427c01 Element 4107786 ×2
  • Sensor, Touch Light Gray Part 879 Element 4247135 or 4209116 ×2

Bricks Sloped 8 pieces

  • Brick Sloped Inverted 33° 3 x 2, Connections between Studs, Ovoid Bottom Pin Blue Part 3747b Element 4509443 ×2
  • Brick Sloped 45° 2 x 1 with Bottom Pin Light Gray Part 3040b Element 4121933 or 304002 ×4
  • Brick Sloped 33° 3 x 1 Yellow Part 4286 Element 428624 ×2

Hinges, Arms and Turntables 8 pieces

  • Arm Piece with Pin, 2 Fingers Black Part 6048a Element 604826 ×2
  • Hinge Brick 1 x 2 Base Black Part 3937 Element 393726 ×2
  • Hinge Brick 1 x 2 Top Plate Thin Black Part 3938 Element 393826 ×2
  • Wing Insectoid Large with Arm Hinge and Circuitry Print Left (Print on Top, Tip on Left, Logo at Back Edge) Trans-Dark Blue Part 30230pr0001 Element 4114643 ×1
  • Wing Insectoid Large with Arm Hinge and Circuitry Print Right (Print on Top, Tip on Right, Logo at Back Edge) Trans-Dark Blue Part 30230pr0002 Element 4114642 ×1

Wheels and Tyres 8 pieces

  • Tyre 20 x 30 Balloon Medium 49.6 x 20 Black Part 6581 Element 658126 ×2
  • Tyre 43 x 17 Black Part 3634 Element 4523564 or 363426 ×2
  • Wheel 20 x 30 Balloon Medium Dark Turquoise Part 6582 Element 4121846 ×2
  • Wheel with Split Axle hole Dark Turquoise Part 3482 Element 4121847 ×2

Tubes and Hoses 6 pieces

  • Hose Rigid 3mm D. 36L / 28.8cm Dark Turquoise Part 75c36 Element 4116939 ×2
  • Hose Rigid 3mm D. 16L / 12.8cm Yellow Part 75c16 Element 4116948 ×2
  • Hose Rigid 3mm D. 44L / 35.2cm Yellow Part 75c44 ×2

String, Bands and Reels 4 pieces

  • Rubber Band Small 13mm (Square Cross Section) Black Part 71509 Element 4141606 or 4107153 ×4

Tiles Special 4 pieces

  • Tile Special 1 x 1 with Clip and Straight Tips Black Part 2555 Element 255526 ×4

Projectiles / Launchers 3 pieces

  • Launcher, Technic Competition Cannon, Round Bottom with Black Ends Dark Turquoise Part 32074c02 Element 4114735 ×1
  • Projectile, Technic Competition Arrow, Beam Shaft with Solid Black Rubber End Yellow Part 76110c01 Element 4114419 ×2

Non-System Parts 2 pieces

  • Ball 41mm Yellow Part 72048 Element 4112928 ×2

Plates Wedged 2 pieces

  • Wedge Plate 3 x 3 Cut Corner Green Part 2450 Element 6529282 or 6114672 ×2

Technic Special 2 pieces

  • Technic Cam Light Gray Part 6575 Element 657502 ×2

Technic Steering, Suspension and Engine 2 pieces

  • Technic Engine Crankshaft Center Light Gray Part 2854 Element 285402 ×2

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.

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