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 Beam 1 x 2 ThinDark Bluish GrayPart 41677Element 6338422 or 4210980×4
Projectiles / Launchers
3 pieces
Launcher, Brick Special 1 x 4 Spring Shooter with Light Bluish Gray TopDark Bluish GrayPart 15400Element 6324200 or 6048898×1
Projectile, Spring Shooter Ammunition 8L BarTrans-Dark BluePart 15303Element 6296379 or 6065898×2
Bricks Curved
2 pieces
Brick Curved 4 x 1 Double, No StudsOrangePart 93273Element 4650977×2
Plates
2 pieces
Plate 1 x 1OrangePart 3024Element 4524929 or 4203454×2
Technic Bushes
2 pieces
Technic Bush 1/2 Smooth with Axle Hole Semi-ReducedLight Bluish GrayPart 32123bElement 6271165 or 4211573×2
Technic Panels
2 pieces
Technic Panel Fairing #21 5L Small Smooth, Side BWhitePart 11946Element 6330084 or 6114580×1
Technic Panel Fairing #22 5L Small Smooth, Side AWhitePart 11947Element 6343987 or 6114583×1
Tiles
2 pieces
Tile 1 x 2 with GrooveBlackPart 3069bElement 306926×1
Tile 2 x 2 with GrooveDark Bluish GrayPart 3068bElement 4211055×1
Bricks Sloped
1 piece
Brick Sloped 18° 2 x 1 x 2/3 with 4 Slots / GrateBlackPart 61409Element 4541191×1
Plates Round Curved and Dishes
1 piece
Plate Round 1 x 1 with Solid StudDark Bluish GrayPart 6141Element 4210633×1
Plates Special
1 piece
Plate Special 2 x 2 with 2 PinsDark Bluish GrayPart 15092Element 6284702 or 6066952×1
Stickers
1 piece
Sticker Sheet for Set 75115-1[No Color/Any Color]Part 25166Element 6137986×1
Technic Beams Special
1 piece
Technic Beam 1 x 3 with Ball Joint in MiddleDark Bluish GrayPart 98577Element 6001085×1
Technic Special
1 piece
Technic Tooth 1 x 3 with Axle Hole [Rounded Underside]BlackPart 41669Element 4540065 or 4177441×1
Tubes and Hoses
1 piece
Hose, Ribbed 7mm D. 14L / 11.2cmBlackPart 78c14Element 6143035 or 4275297×1
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.