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 Brick 1 x 2 [1 Pin Hole]RedPart 3700Element 370021×2
Flat Silver
9 pieces
Animal Body Part, Barb / Claw / Tooth / Talon / Horn, SmallFlat SilverPart 53451Element 6270108 or 46129011 spare in the box×2
Large Figure Face 4 x 5 x 1 2/3 with Helmet, Red Visor, Dark Red Stripes (Ant-Man) PrintFlat SilverPart 85834pr0006Element 6488500 or 6433841×1
Tile Special 1 x 2 with Sloped Walls AKA Money / Gold Bar [Ingot]Flat SilverPart 99563Element 6208446×6
Trans-Red
5 pieces
Plate 1 x 2Trans-RedPart 3023Element 6514003 or 6240212×2
Tile Round 1 x 1Trans-RedPart 98138Element 6514189 or 62586071 spare in the box×3
White
3 pieces
Technic Brick 1 x 2 [2 Pin Holes]WhitePart 32000Element 6564911 or 3200001×2
Technic Brick Special 2 x 2 with Ball Socket Wide and Axle Hole, No Arm HolesWhitePart 67696Element 6360826×1
Yellow
3 pieces
Plate 2 x 2YellowPart 3022Element 4613978 or 302224×2
Technic Axle 3YellowPart 4519Element 6130007×1
Trans-Clear
1 piece
Bar, Angled with 1 x 1 Round Plate / Stud on EndTrans-ClearPart 65578Element 6510188 or 62855871 spare in the box×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.