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.
Builders who report a missing piece often find it in one of these places. Tick each one off as you look.
Look-alike colors in this set
These parts appear in this set in two colors that are easy to confuse. If you are one short in one color,
check whether it went in where the other color belongs. Each color has its own element ID in the parts list
at the back of the instructions.
Technic Beam 1 x 5 ThickBlack ×1Dark Bluish Gray ×5Black is darker than Dark Bluish Gray.
Technic Beam 1 x 7 ThickBlack ×2Dark Bluish Gray ×4Black is darker than Dark Bluish Gray.
Technic Beam 1 x 9 ThickBlack ×7Dark Bluish Gray ×2Black is darker than Dark Bluish Gray.
Technic Beam 2 x 3 Thick [90° Offset Centre Beam Hole]Black ×2Dark Bluish Gray ×4Black is darker than Dark Bluish Gray.
Technic Beam 3 x 5 L-Shape ThickBlack ×4Dark Bluish Gray ×2Black is darker than Dark Bluish Gray.
Technic Driving Ring Connector Smooth [2 rounded and 2 flat side walls]Black ×7Dark Bluish Gray ×2Black is darker than Dark Bluish Gray.
Technic Axle 5 with StopReddish BrownPart 15462Element 6159763×3
White
3 pieces
Technic Axle Pin 3L without Friction Ridges and 2L AxleWhitePart 65249Element 6289797×3
Green
2 pieces
Plate Round 1 x 1 with Open StudGreenPart 85861Element 63382211 spare in the box×2
Pearl Gold
2 pieces
Technic Pin Connector Round [Slotted]Pearl GoldPart 62462Element 6390147 or 6245500×2
Trans-Orange
2 pieces
Dome 1 x 1 x 2/3Trans-OrangePart 6908Element 65097761 spare in the box×1
Minifig Head [Plain] [Vented Stud - 2 Holes]Trans-OrangePart 28621Element 6513998 or 6395071×1
[No Color/Any Color]
1 piece
Sticker Sheet for Set 42239-1[No Color/Any Color]Part 10115258Element 6580442×1
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.