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 142 pieces. This inventory comes from a separate parts catalog and lists 143; 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.
Battery Box, 9V Small [Complete Assembly]BlackPart 4760c01Element 4109849×1
Wire with Brick 2 x 2 x 2/3 Pair, 20LBlackPart 5306bc020Element 4100355×1
Motor, 9V Mini [Old Style]Light GrayPart 71427c01Element 4107786×1
Bricks Special
2 pieces
Brick Special 2 x 2 with Pin and Axle HoleLight GrayPart 6232Element 623202×2
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.
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.