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.
Arm Mechanical with Clip [Thick Support]WhitePart 98313Element 6976864 or 6276864×4
Plates Round Curved and Dishes
4 pieces
Plate Round 1 x 1 with Solid StudTrans-Light BluePart 6141Element 6514058 or 62402251 spare in the box×4
Technic Pins
3 pieces
Technic Pin Long with Friction Ridges Lengthwise, 2 Center SlotsBluePart 6558Element 4514553×1
Technic Pin 1/2 with 2L Bar ExtensionLight Bluish GrayPart 61184Element 6347715 or 4520320×2
Technic Steering, Suspension and Engine
2 pieces
Technic Engine CrankshaftLight Bluish GrayPart 2853Element 6640384 or 4211609×2
Energy Effects
1 piece
Large Figure Weapon Accessory, Flame / Lightning Bolt with Axle Hole with Marbled Trans-Light Blue PatternWhitePart 11302pat0003Element 6266807 or 6029783×1
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.