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.
367 pieces in 114 part and color combinations, plus 4 minifigures.
The official piece count includes the 12 parts inside the set's minifigures, which this inventory lists separately. Spare parts are counted in neither figure.
Before you call it missing
Builders who report a missing piece often find it in one of these places. Tick each one off as you look.
Technic Axle 4RedPart 3705Element 6129995 or 4265797×2
Technic Rubber Belt Medium [24mm ID] [Round Cross Section]RedPart 85544Element 4544145 or 4544143×2
Tan
4 pieces
Technic Gear 20 Tooth Double Bevel with Axle Hole Type 1 [+ Opening]TanPart 18575Element 6346517 or 6084724×4
Blue
2 pieces
Brick 2 x 4BluePart 3001Element 300173 or 300123×2
Bright Light Orange
2 pieces
Brick 2 x 4Bright Light OrangePart 3001Element 6100027 or 4645053×2
Green
2 pieces
Brick 2 x 4GreenPart 3001Element 4106356 or 300128×2
Medium Lavender
2 pieces
Brick 2 x 4Medium LavenderPart 3001Element 6013583 or 4655173×2
[No Color/Any Color]
2 pieces
Activity Card ? for Science Kits[No Color/Any Color]Part 119190Element 6633001×2
Minifigures
4 figures
Monochrome Bright GreenMinifigure, checked as a whole figure×1
Monochrome Red, 28621 HeadMinifigure, checked as a whole figure×1
Monochrome BlueMinifigure, checked as a whole figure×1
Monochrome Bright Light Orange, 28621 HeadMinifigure, checked as a whole figure×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.