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 Beam 1 x 2 with Ball Joint AngledDark Bluish GrayPart 50923Element 4503381 or 4289258×2
Technic Beam 1 x 3 with Ball Joint in MiddleDark Bluish GrayPart 98577Element 6001085×3
Technic Bushes
4 pieces
Technic Bush 1/2 Smooth with Axle Hole Semi-ReducedYellowPart 32123bElement 6271167 or 32123241 spare in the box×4
Transportation - Sea and Air
4 pieces
Propeller 1 Blade 2 x 16 with AxleYellowPart 98135Element 6030936×4
Plates Round Curved and Dishes
2 pieces
Plate Round 2 x 2 with Axle Hole Type 1 (+ Opening)BluePart 4032aElement 403223×1
Plate Round 2 x 2 with Rounded Bottom [Boat Stud]RedPart 2654Element 4617080 or 4278275×1
String, Bands and Reels
1 piece
Rubber Belt Small [15mm ID] [Round Cross Section]WhitePart 85543Element 6699001 or 4580665×1
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.