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 Axle 6RedPart 3706Element 6130002 or 4191526×2
Technic Beam 1 x 3 ThickRedPart 32523Element 4153718×2
Technic Pin Long with Friction Ridges Lengthwise and Stop Bush [3 Lateral Holes, Big Pin Hole]RedPart 32054Element 4140806 or 4125198×6
Reddish Brown
14 pieces
Technic Axle 3 with StopReddish BrownPart 24316Element 6135494×12
Technic Axle 5 with StopReddish BrownPart 15462Element 6159763×2
Yellow
8 pieces
Technic Axle 5YellowPart 32073Element 6130008×4
Technic Axle 9YellowPart 60485Element 6130010×2
Technic Beam 1 x 3 ThickYellowPart 32523Element 4153707×2
Green
2 pieces
Technic Beam 1 x 3 ThickGreenPart 32523Element 6007973 or 4158868×2
[No Color/Any Color]
1 piece
Sticker Sheet for Set 51515-1[No Color/Any Color]Part 73229Element 6327015×1
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.