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 1,677 pieces. This inventory comes from a separate parts catalog and lists 1,684; 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.
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 7 ThickBlack ×13Dark Bluish Gray ×10Black is darker than Dark Bluish Gray.
Technic Steering Arm 5.5 x 2 with Towball Socket Rounded, Chamfered [Reinforced]Dark Bluish GrayPart 64872Element 6278260×4
Technic Steering Hub for Portal AxleDark Bluish GrayPart 92909Element 4610378×4
Yellow
42 pieces
Technic Axle 5YellowPart 32073Element 6130008×20
Technic Beam 1 x 13 ThickYellowPart 41239Element 4522935 or 4237328×1
Technic Beam 3 x 5 L-Shape with Quarter Ellipse ThinYellowPart 32250Element 6522621 or 6371956×4
Technic Engine CrankshaftYellowPart 2853Element 6640378 or 4119474×2
Technic Engine Piston RoundYellowPart 2851Element 4112203 or 285124×8
Technic Shock Absorber 6.5L with Hard Spring, Tight Coil in Middle [Complete Assembly]YellowPart 76537Element 7653726 or 6027566×4
Tile 1 x 1 with GrooveYellowPart 3070bElement 307024×1
Tile 1 x 6 with GrooveYellowPart 6636Element 6388488 or 663624×2
Tan
19 pieces
Technic Axle 4 with Centre StopTanPart 99008Element 4666999×1
Technic Axle Pin without Friction Ridges LengthwiseTanPart 3749Element 4666579 or 4186017×1
Technic Engine Crankshaft CenterTanPart 2854Element 6355727 or 6013937×3
Technic Gear 12 Tooth BevelTanPart 6589Element 4565452 or 4514556×3
Technic Gear 20 Tooth Double Bevel with Axle Hole Type 1 [+ Opening]TanPart 18575Element 6346517 or 6084724×1
Technic Pin 3/4TanPart 32002Element 6663097 or 6013938×6
Technic Pin Long without Friction Ridges, with Anti-Roll NotchTanPart 39888Element 6321305×4
Reddish Brown
7 pieces
Technic Axle 3 with StopReddish BrownPart 24316Element 6135494×6
Technic Axle 5 with StopReddish BrownPart 15462Element 6159763×1
Flat Silver
4 pieces
Brick Round 1 x 1 diameter Tube with 90 Degree Elbow (2 x 2 x 1) and Axle Holes (Crossholes) at each endFlat SilverPart 25214Element 6335563×2
Technic Pin Connector Round [Slotted]Flat SilverPart 62462Element 6245499 or 6054858×2
Trans-Red
4 pieces
Brick Round 2 x 2 with Axle HoleTrans-RedPart 3941Element 6514289 or 6334501×2
Plate Round 2 x 2 with Rounded Bottom [Boat Stud]Trans-RedPart 2654Element 6581776 or 6254635×2
Trans-Clear
2 pieces
Windscreen 6 x 4 x 1 Curved with Headlights, Grill, Red Bodywork PrintTrans-ClearPart 18973pr0009Element 6335199×1
Windscreen 6 x 4 x 1 Curved with Headlights, Grill, Red Bodywork PrintTrans-ClearPart 18973pr0010Element 6335200×1
[No Color/Any Color]
2 pieces
Sticker Sheet 1 for Set 42125-1[No Color/Any Color]Part 72212Element 6323458×1
Sticker Sheet 2 for Set 42125-1[No Color/Any Color]Part 77422Element 6337818×1
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.