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.
Wheel 11 x 8 with Center GrooveLight Bluish GrayPart 42610Element 4211758×3
Blue
63 pieces
Technic Axle Pin with Friction Ridges LengthwiseBluePart 43093Element 4309323 or 42064821 spare in the box×33
Technic Beam 2 x 4 L-Shape ThickBluePart 32140Element 6271829 or 4168114×2
Technic Pin Long with Friction Ridges Lengthwise, 2 Center SlotsBluePart 6558Element 4514553×28
Dark Bluish Gray
8 pieces
Technic Axle 5.5 with Stop [Rounded Short End]Dark Bluish GrayPart 59426Element 4508553×2
Technic Axle 8 with StopDark Bluish GrayPart 55013Element 4499858×1
Technic Gear 24 Tooth [New Style with Single Axle Hole]Dark Bluish GrayPart 3648bElement 6133119 or 4514558×2
Technic Gear 8 ToothDark Bluish GrayPart 3647Element 45145591 spare in the box×3
Tan
2 pieces
Technic Axle Pin without Friction Ridges LengthwiseTanPart 3749Element 4666579 or 4186017×2
[No Color/Any Color]
1 piece
Sticker Sheet for Set 9394-1[No Color/Any Color]Part 71507Element 4654702×1
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.