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.
Technic Pin 1/2 without Friction RidgesLight Bluish GrayPart 4274Element 4274194 or 4211483×2
Yellow
2 pieces
Cone 1 x 1 [Top Groove]YellowPart 59900Element 4525464×1
Technic Axle and Pin Connector Angled #1YellowPart 32013Element 6329889 or 4107066×1
Blue
1 piece
Technic Pin Long with Friction Ridges Lengthwise, 2 Center SlotsBluePart 6558Element 4514553×1
Bright Green
1 piece
Plate 6 x 12Bright GreenPart 3028Element 4541414×1
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.
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.