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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.

Robo Technology Set (Serial Cable)

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9785 Robo Technology Set (Serial Cable)

221 pieces in 68 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

Light Gray 68 pieces

  • Cable, Serial, for IR Transmitter Tower Light Gray Part 71793 Element 4119830 ×1
  • Motor, 9V Mini [Old Style] Light Gray Part 71427c01 Element 4107786 ×2
  • Plate 2 x 10 Light Gray Part 3832 Element 383202 ×2
  • Sensor, Touch Light Gray Part 879 Element 4247135 or 4209116 ×2
  • Technic Axle 1.5 with Perpendicular Axle Connector (Technic Pole Reverser Handle) Light Gray Part 6553 Element 655302 ×4
  • Technic Axle 3 Light Gray Part 4519 Element 4186007 ×2
  • Technic Axle 5 Light Gray Part 32073 Element 4141482 ×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 Perpendicular Light Gray Part 6536 Element 4173667 or 653602 ×2
  • 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 Gear 8 Tooth Light Gray Part 3647 Element 364702 ×3
  • 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

Black 45 pieces

  • Hair Ponytail Black Part 6093 Element 609376 or 609326 ×1
  • Plate Round 2 x 2 with Rounded Bottom [Boat Stud] Black Part 2654 Element 4617551 or 4278359 ×2
  • 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 4 Black Part 3705 Element 370526 ×2
  • Technic Axle 6 Black Part 3706 Element 370626 ×2
  • Technic Axle 8 Black Part 3707 Element 370726 ×2
  • Technic Brick 1 x 16 [15 Pin Holes] Black Part 3703 Element 370326 ×2
  • Technic Pin with Friction Ridges Lengthwise and Center Slots Black Part 2780 Element 4121715 or 278026 ×12
  • Technic Wedge Belt Wheel Tire Black Part 2815 Element 6028041 or 281526 ×2
  • Tyre 43 x 17 Black Part 3634 Element 4523564 or 363426 ×2
  • Tyre 81.6 x 15 Motorcycle Black Part 2902 Element 6226880 or 4562873 ×2
  • Tyre Offset Tread 24 x 8 Black Part 3483 Element 4501048 or 348326 ×2
  • Wire with Brick 2 x 2 x 2/3 Pair, 20L Black Part 5306bc020 Element 4100355 ×3
  • Wire with Brick 2 x 2 x 2/3 Pair, 36L Black Part 5306bc036 Element 75652 ×3

Blue 40 pieces

  • Bracket 2 x 2 - 2 x 2 Blue Part 3956 Element 6019215 or 395623 ×2
  • Hips and Blue Legs Blue Part 970c28 Element 6006026 or 4583501 ×1
  • Plate 1 x 2 Blue Part 3023 Element 302323 ×8
  • Plate 1 x 8 Blue Part 3460 Element 346023 ×2
  • Sensor, Light with Fixed Cable Blue Part 2982c01 Element 4119421 ×1
  • Technic Beam 3 x 5 L-Shape with Quarter Ellipse Thin Blue Part 32250 Element 6371955 or 6339225 ×2
  • 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 ×2
  • Technic Brick 1 x 2 [1 Pin Hole] Blue Part 3700 Element 370023 ×4
  • 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 ×4
  • Technic Plate 2 x 6 [5 Holes] Blue Part 32001 Element 4114027 or 3200123 ×4
  • Technic Rubber Belt Medium [24mm ID] [Round Cross Section] Blue Part 85544 ×4

Yellow 21 pieces

  • Brick 2 x 2 Yellow Part 3003 Element 4103588 or 300374 ×6
  • Hub, RCX 2.0, No Power Jack [Complete Assembly] Yellow Part 884c ×1
  • Technic Plate 2 x 4 [3 Holes] Yellow Part 3709 Element 370924 ×4
  • Technic Plate 2 x 8 [7 Holes] Yellow Part 3738 Element 4624216 or 373824 ×4
  • Technic Wedge Belt Wheel [aka Pulley] Yellow Part 4185 Element 6636439 or 6363273 ×2
  • Wheel with Split Axle hole Yellow Part 3482 Element 348224 ×4

Dark Gray 11 pieces

  • Technic Axle 3 with Stud Dark Gray Part 6587 Element 4113884 or 658727 ×2
  • Technic Pin 3/4 Dark Gray Part 32002 Element 4109854 ×8
  • Transmitter Tower, IR, Serial with Black Front Dark Gray Part 76091 Element 4121506 ×1

Red 10 pieces

  • Brick 2 x 4 Red Part 3001 Element 300121 ×6
  • Plate 6 x 12 Red Part 3028 Element 4617409 or 4288289 ×2
  • Technic Gear 24 Tooth [New Style with Single Axle Hole] Red Part 3648b Element 4142825 ×2

Tan 8 pieces

  • Technic Axle Pin without Friction Ridges Lengthwise Tan Part 3749 Element 4666579 or 4186017 ×8

Green 6 pieces

  • Technic Brick 1 x 2 with Axle Hole Type 2 [X Opening] Green Part 32064b ×4
  • Technic Gear 40 Tooth Green Part 3649 Element 4120109 ×2

White 4 pieces

  • Light Brick 1 x 2 with Single Side Light White Part 6035 Element 4603220 or 74880 ×1
  • Torso, White Arms, Yellow Hands [Plain] White Part 973c27h01 Element 6038496 or 4275461 ×1
  • Wheel 61.6 x 13.6 Motorcycle White Part 2903 Element 290301 ×2

Purple 2 pieces

  • Hose, Ribbed 7mm D. 12L / 9.6cm Purple Part 78c12 Element 4275294 or 4114738 ×2

Trans-Neon Green 2 pieces

  • Dome Hemisphere 4 x 4 Multifaceted Trans-Neon Green Part 30208 Element 6031104 or 4114690 ×2

Bright Green 1 piece

  • Storage Bin, Dacta, Medium Bright Green Part upn0038 ×1

Brown 1 piece

  • Hair Smooth Brown Part 3901 Element 390175 or 390125 ×1

Trans-Clear 1 piece

  • Storage Bin Lid, Dacta, 19 x 24 Trans-Clear Part 71082 ×1

[No Color/Any Color] 1 piece

  • Playmat / Test Mat for Mindstorms for Schools - Training Missions Activity Pad [No Color/Any Color] Part 45533 Element 4189432 ×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

Buy the piece

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.

Keep a record

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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