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 Connector Round with 4 ClipsReddish BrownPart 90202Element 6349130×1
Technic Pins
9 pieces
Technic Axle Pin 3L with Friction Ridges Lengthwise and 2L AxleBlackPart 18651Element 6089119×1
Technic Pin 1/2 with FrictionRedPart 89678Element 63781201 spare in the box×8
Bricks Wedged
8 pieces
Brick Wedged, Curved 2 x 1 with Stud Notch LeftDark RedPart 29120Element 6219658×2
Brick Wedged, Curved 2 x 2 with Stud NotchesDark RedPart 66956Element 6312350×6
Minifig Shields, Weapons, & Tools
6 pieces
Weapon Gun Automatic Pistol Medium BarrelBlackPart 62885Element 6103643 or 6052829×6
Tiles Special
5 pieces
Tile Special Round 2 x 2 with HoleDark TanPart 15535Element 6132790×1
Tile Special Round 1 x 1 with Hollow BarYellowish GreenPart 20482Element 62235061 spare in the box×4
Minifig Headwear
4 pieces
Hat, Forestmen (Reissue with Blind Hole for Feather)GreenPart 88489Element 6527055 or 6414961×4
Wheels and Tyres
2 pieces
Technic Wedge Belt Wheel [aka Pulley]BlackPart 4185Element 6323668 or 6192130×2
Tools
1 piece
Brick and Axle Separator v2.0OrangePart 96874Element 6240515 or 4654448×1
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.