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.
LEGO counts 179 pieces. This inventory comes from a separate parts catalog and lists 180; the two do not always count the same elements, so their totals differ. 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 5Light Bluish GrayPart 32073Element 32073194 or 4211639×2
Technic Bush 1/2 Smooth with Axle Hole ReducedLight Bluish GrayPart 32123a×3
Technic Connector Block 3 x 3 Triangular with Axle, and Pin HoleLight Bluish GrayPart 32175Element 4249274 or 4227602×2
Technic Pin Long without Friction Ridges - Single SlotLight Bluish GrayPart 32556aElement 4211709×4
Technic Pin without Friction Ridges LengthwiseLight Bluish GrayPart 3673Element 4211807 or 3673194×6
Blue
9 pieces
Technic Axle Pin with Friction Ridges LengthwiseBluePart 43093Element 4309323 or 4206482×9
Red
6 pieces
Large Figure Mask Kiril with Marbled Black Pattern (Dume)RedPart 47327pat0001Element 4288676 or 4237005×1
Large Figure Skeletal, Limb, Angular 90°, 4 x 4 x 2 with 2 Ball Joints, and Axle HoleRedPart 41670Element 4289878 or 4192715×4
Large Figure Skeletal, Torso with 6 Holes (Matoran)RedPart 47295Element 4227599×1
Dark Bluish Gray
5 pieces
Technic Axle 3 with StudDark Bluish GrayPart 6587Element 6587199 or 6129590×5
Trans-Neon Orange
3 pieces
Large Figure Head Connector Block Eye/Brain StalkTrans-Neon OrangePart 32554Element 4143501×1
Technic Tooth 1 x 3 with Axle Hole [Rounded Underside]Trans-Neon OrangePart 41669Element 6111281 or 4163574×2
Tan
2 pieces
Technic Axle Pin without Friction Ridges LengthwiseTanPart 3749Element 4666579 or 4186017×2
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.