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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.

Master Builder Set

Checking

10023 Master Builder Set

111 pieces in 44 part and color combinations.

LEGO counts 102 pieces. This inventory comes from a separate parts catalog and lists 111; the two do not always count the same elements, so their totals differ. Spare parts are counted in neither figure.

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 23 pieces

  • Technic Pin Double with Axle Hole Black Part 32138 Element 4130597 or 4119589 ×1
  • Technic Pin with Friction Ridges Lengthwise and Center Slots Black Part 2780 Element 4121715 or 278026 ×5
  • Technic Axle Pin without Friction Ridges Lengthwise Light Gray Part 3749 Element 4184168 or 4154179 ×5
  • Technic Pin 1/2 without Friction Ridges Light Gray Part 4274 Element 427402 ×3
  • Technic Pin Long without Friction Ridges - Single Slot Light Gray Part 32556a Element 4154753 ×4
  • Technic Pin without Friction Ridges Lengthwise Light Gray Part 3673 Element 4184166 or 367302 ×5

Technic Connectors 19 pieces

  • Technic Axle Connector with Axle Hole Dark Gray Part 32039 Element 4141420 ×2
  • Technic Axle and Pin Connector Angled #5 - 112.5° Dark Gray Part 32015 Element 4106383 ×2
  • Technic Axle and Pin Connector Perpendicular Dark Gray Part 6536 Element 4173659 or 4141206 ×4
  • Technic Axle and Pin Connector Perpendicular Double Dark Gray Part 32291 Element 4140475 or 4130189 ×2
  • Technic Block 3 x 5 x 1 2/3 Dark Gray Part 32310 Element 4140476 or 4130191 ×1
  • Technic Axle Connector 2 x 3 with Ball Socket, Open Sides Orange Part 32174 Element 4257235 or 4142053 ×2
  • Technic Axle and Pin Connector Angled #3 - 157.5° Orange Part 32016 Element 6366185 or 6251180 ×4
  • Technic Gearbox Half Red Part 32166 Element 4155823 ×2

Technic Axles 16 pieces

  • Technic Axle 2 Notched Black Part 32062 Element 4109810 or 3206226 ×7
  • Technic Axle 3 Black Part 4519 Element 6238084 or 451926 ×2
  • Technic Axle 4 Black Part 3705 Element 370526 ×4
  • Technic Axle 6 Black Part 3706 Element 370626 ×2
  • Technic Axle 8 Black Part 3707 Element 370726 ×1

Technic Beams 12 pieces

  • Technic Beam 1 x 3 Thin Black Part 6632 Element 6331723 or 4107828 ×2
  • Technic Beam 1 x 5 Thick Dark Gray Part 32316 Element 4142136 or 4141430 ×2
  • Technic Beam 1 x 7 Bent (4 - 4) Thick Dark Gray Part 32348 Element 4140477 ×2
  • Technic Beam 1 x 7 Thick Dark Gray Part 32524 Element 4154760 ×2
  • Technic Beam 1 x 9 Bent (7 - 3) Thick Dark Gray Part 32271 Element 4141428 ×2
  • Technic Beam 2 x 4 L-Shape Thick Dark Gray Part 32140 Element 4141417 ×2

Technic Bushes 10 pieces

  • Technic Bush Light Gray Part 3713 Element 4125313 or 659002 ×5
  • Technic Bush 1/2 Smooth with Axle Hole Reduced Light Gray Part 32123a ×5

Large Buildable Figures 8 pieces

  • Large Figure Foot, with Ball Joint Socket 3 x 6 x 2 1/3 Dark Gray Part 32475 Element 4155824 ×1
  • Large Figure Head Connector Block 3 x 4 x 1 2/3 Dark Gray Part 32553 Element 4154758 ×1
  • Large Figure Mask Pakari Orange Part 32566 Element 4173537 ×1
  • Large Figure Skeletal, Limb, Angular with Ball Joint, and Axle Hole Orange Part 32476 Element 4194112 or 4143516 ×2
  • Large Figure Weapon, Claw, Triple, with Axle Orange Part 32506 Element 4158030 or 4154618 ×2
  • Large Figure Weapon, Claw Hook with Axle Red Part 32551 Element 4153715 ×1

String, Bands and Reels 4 pieces

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

Technic Gears 4 pieces

  • Technic Worm Gear Black Part 4716 Element 6037533 or 471626 ×1
  • Technic Gear 24 Tooth [New Style with Single Axle Hole] Dark Gray Part 3648b Element 4179753 or 4141308 ×1
  • Technic Gear 8 Tooth Dark Gray Part 3647 Element 4155821 ×2

Technic Special 4 pieces

  • Technic Ball Joint Black Part 32474 Element 4290713 or 4143539 ×4

Tubes and Hoses 4 pieces

  • Hose, Ribbed 7mm D. 2L / 1.6cm Pearl Light Gray Part 78c02 Element 4495192 or 4275384 ×3
  • Hose Rigid 3mm D. 3L / 2.4cm Red Part 75c03 Element 4155926 1 spare in the box ×1

Plates Round Curved and Dishes 3 pieces

  • Plate Round 1 x 1 with Solid Stud Trans-Red Part 6141 Element 6514051 or 6208450 ×3

Technic Beams Special 2 pieces

  • Technic Beam 1 x 7 with Fan Dark Gray Part 32177 Element 4130188 or 4124033 ×2

Technic Panels 2 pieces

  • Technic Panel Fairing # 5 Small Short, Large Hole, Side A Red Part 32527 Element 4143152 ×1
  • Technic Panel Fairing # 6 Small Short, Large Hole, Side B Red Part 32528 Element 4143150 ×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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