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 Gear 8 ToothLight Bluish GrayPart 3647Element 4211432 or 3647194×1
Technic Gear Rack 1 x 4Light Bluish GrayPart 3743Element 6457283 or 4211450×1
Plates
6 pieces
Plate 1 x 2BlackPart 3023Element 302326×2
Plate 1 x 4BlackPart 3710Element 371026×1
Plate 1 x 2RedPart 3023Element 302321×1
Plate 1 x 8RedPart 3460Element 346021×2
Bars, Ladders and Fences
4 pieces
Fence Lattice 1 x 4 x 2BlackPart 3185Element 4188953 or 4106485×4
Bricks Round and Cones
4 pieces
Brick Round 2 x 2 with Axle HoleTrans-RedPart 3941Element 6514289 or 6334501×4
Technic Special
4 pieces
Technic Disc 3 x 3BlackPart 2723Element 4218868 or 4121619×2
Technic Tooth 1 x 3 with Axle Hole [Rounded Underside]RedPart 41669Element 4185661×2
Technic Beams Special
2 pieces
Technic Beam 3 x 0.5 Liftarm with Boss and Pin / CrankLight Bluish GrayPart 33299aElement 4211688×2
Technic Bricks
2 pieces
Technic Pin Connector Block 1 x 5 x 3BlackPart 32333Element 6271358 or 4141810×2
Bricks
1 piece
Brick 1 x 2BlackPart 3004Element 300426×1
Stickers
1 piece
Sticker Sheet for Set 8653-1[No Color/Any Color]Part 53294Element 4267882×1
Tiles
1 piece
Tile 1 x 2 with GrooveBlackPart 3069bElement 306926×1
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.