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.
LEGO counts 643 pieces. This inventory comes from a separate parts catalog and lists 644; 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.
Rubber Belt Small [15mm ID] [Round Cross Section]WhitePart 85543Element 6699001 or 4580665×5
Blue
3 pieces
Technic Reel 3 x 2BluePart 32012Element 4107179×1
Technic Rubber Belt Medium [26mm ID] [Round Cross Section]BluePart 85545Element 6049730 or 4544147×2
[No Color/Any Color]
3 pieces
CD-Rom, for 8450[No Color/Any Color]Part upn0135×1
Sticker Sheet 1 for Set 8450-1[No Color/Any Color]Part 22251Element 4124181×1
Sticker Sheet 2 for Set 8450-1[No Color/Any Color]Part 22512Element 4125362×1
Trans-Green
2 pieces
Plate Round 1 x 1 with Solid StudTrans-GreenPart 6141Element 6514057 or 6240221×2
Trans-Red
2 pieces
Plate Round 1 x 1 with Solid StudTrans-RedPart 6141Element 6514051 or 6208450×2
Trans-Clear
1 piece
Technic Shock Absorber 10L, Damped, Normal SpringTrans-ClearPart 76320c01Element 4142095×1
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.