Free tool

LEGO Missing Piece Checker

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.

Checking

42108 Mobile Crane

1,292 pieces in 145 part and color combinations.

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.

Every bag and the box. Shake out each bag, check its corners and seams, and look inside the empty box.
Inside what you have built. Small pieces lodge inside tubes, under plates and between studs. Turn the model over and look.
The last few steps. Compare each recent step with its parts callout. A piece used in the wrong place earlier leaves you one short later.
Look-alike colors. Compare each color with the step's parts callout, especially White against Trans-Clear.
The spare pieces. This set comes with 12 spare pieces, marked on each row of the checklist. One may be the piece you need.
The floor and your building area. Check under furniture, the chair and the edges of your building surface.

Piece checklist

Technic Bushes 29 pieces

Technic Bush Red Part 3713 Element 6271820 or 4227155 1 spare in the box ×6
Technic Bush 1/2 Smooth with Axle Hole Semi-Reduced Yellow Part 32123b Element 6271167 or 3212324 1 spare in the box ×23

Technic Panels 28 pieces

Technic Panel Curved and Bent 6 x 3 Black Part 24116 Element 6268012 or 6133246 ×4
Technic Panel Fairing # 3 Small Smooth Long, Side A Black Part 64683 Element 4541924 ×1
Technic Panel Fairing # 4 Small Smooth Long, Side B Black Part 64391 Element 4541325 ×1
Technic Panel Curved and Bent 6 x 3 Blue Part 24116 Element 6268009 or 6133684 ×4
Technic Panel 3 x 11 x 1 Yellow Part 15458 Element 6143847 ×1
Technic Panel Curved 11 x 3 with 10 Pin Holes through Panel Surface Yellow Part 11954 Element 6251202 or 6022952 ×11
Technic Panel Curved and Bent 6 x 3 Yellow Part 24116 Element 6268010 or 6133245 ×4
Technic Panel Fairing #5 Long Smooth, Side A Yellow Part 64681 Element 6286376 or 4558817 ×1
Technic Panel Fairing #6 Long Smooth, Side B Yellow Part 64393 Element 6065491 or 4558800 ×1

Technic Beams Special 27 pieces

Technic Beam 3 x 0.5 Liftarm with Boss and Blocked, Squared Pin Hole Black Part 61408 Element 6313520 ×3
Technic Beam Frame 5 x 7 with 3 x 5 Opening Thick Black Part 64179 Element 6016154 ×1
Technic Pin Connector Double with Bar [2 Holes] Black Part 85940 Element 6173124 or 4562148 ×2
Technic Beam 3 x 0.5 Liftarm with Boss and Blocked, Squared Pin Hole Light Bluish Gray Part 61408 Element 6331859 ×10
Technic Beam 5 x 11 with 3 x 5 Opening Frame Thick Light Bluish Gray Part 64178 Element 4540797 ×2
Technic Beam Frame 5 x 7 with 3 x 5 Opening Thick Light Bluish Gray Part 64179 Element 4539880 ×4
Technic Beam 3 x 5 Thick [90° Offset Centre Beam Holes] Yellow Part 14720 Element 6259054 ×5

Tiles Round and Curved 26 pieces

Tile Round 1 x 1 Trans-Clear Part 98138 Element 6514191 or 6274738 1 spare in the box ×8
Tile Round 1 x 1 Trans-Green Part 98138 Element 6514194 or 6274742 1 spare in the box ×1
Tile Round 1 x 1 Trans-Orange Part 98138 Element 6514197 or 6274747 1 spare in the box ×12
Tile Round 1 x 1 Trans-Red Part 98138 Element 6514189 or 6258607 1 spare in the box ×5

Wheels and Tyres 20 pieces

Tyre 49.53 x 20 Black Part 15413 Element 6518565 or 6055626 ×8
Technic Wedge Belt Wheel [aka Pulley] Light Bluish Gray Part 4185 Element 6321743 or 4494222 ×1
Wheel 18 x 8 with Fake Bolts and Deep Spokes with Inner Ring Light Bluish Gray Part 13971 Element 6359807 or 6044729 ×3
Wheel 30.4 x 20 without Pinholes, with Reinforced Rim Yellow Part 56145 Element 6286380 or 4490139 ×8

Bricks Round and Cones 11 pieces

Brick Round 1 x 1 diameter Tube with 90 Degree Elbow (2 x 2 x 1) and Axle Holes (Crossholes) at each end Black Part 25214 Element 6179182 ×6
Brick Round 2 x 2 [Grill] Black Part 92947 Element 6024730 ×3
Brick Round 2 x 2 with Axle Hole Trans-Orange Part 3941 Element 6514283 or 6273154 ×2

Plates Round Curved and Dishes 11 pieces

Plate Round 1 x 1 with Open Stud Black Part 85861 Element 6168646 or 6100627 1 spare in the box ×5
Plate Round 2 x 2 with Rounded Bottom [Boat Stud] Black Part 2654 Element 4617551 or 4278359 ×3
Plate Special 1 x 2 Rounded with 2 Open Studs Black Part 35480 Element 6210270 ×1
Plate Round 2 x 2 with Rounded Bottom [Boat Stud] Trans-Orange Part 2654 Element 6513980 or 6171727 ×2

Tiles 11 pieces

Tile 1 x 6 with Groove Black Part 6636 Element 663626 ×7
Tile 1 x 4 with Groove Light Bluish Gray Part 2431 Element 4211356 or 2431194 ×3
Tile 2 x 2 Corner Light Bluish Gray Part 14719 Element 6065824 ×1

Plates 10 pieces

Plate 1 x 2 Black Part 3023 Element 302326 ×1
Plate 1 x 3 Black Part 3623 Element 362326 ×4
Plate 1 x 4 Black Part 3710 Element 371026 ×1
Plate 2 x 12 Black Part 2445 Element 244526 ×3
Plate 2 x 8 Black Part 3034 Element 303426 ×1

Technic Bricks 8 pieces

Technic Brick 1 x 10 [9 Pin Holes] Black Part 2730 Element 273026 ×1
Technic Brick 1 x 12 [11 Pin Holes] Black Part 3895 Element 389526 ×6
Technic Brick 1 x 4 [3 Pin Holes] Black Part 3701 Element 370126 ×1

Tiles Special 5 pieces

Tile Special Round 2 x 2 with Hole Black Part 15535 Element 6143850 ×5

String, Bands and Reels 2 pieces

String Cord Medium Thickness (1mm) 300cm Dark Bluish Gray Part 37597c300 Element 6225933 ×1
Chain 16L [21 Links] Light Bluish Gray Part 60169 Element 6292172 or 4512049 ×1

Technic Special 2 pieces

Technic Disc 3 x 3 Black Part 2723 Element 4218868 or 4121619 ×1
Technic Linear Actuator with Dark Bluish Gray Ends Long Light Bluish Gray Part 40918 Element 6240630 ×1

Technic Steering, Suspension and Engine 2 pieces

Technic Engine Crankshaft Light Bluish Gray Part 2853 Element 6640384 or 4211609 ×1
Technic Steering Wheel Small (3 Studs Diameter) Light Bluish Gray Part 2819 Element 4580510 or 4211578 ×1

Bricks Curved 1 piece

Brick Curved 4 x 1 Double, No Studs Black Part 93273 Element 4613153 ×1

Plates Special 1 piece

Plate Special 1 x 1 with Clip Light, Bar Hole [Thick Ring] Black Part 4081b Element 6281993 or 4632571 ×1

Stickers 1 piece

Sticker Sheet for Set 42108-1 [No Color/Any Color] Part 65625 Element 6283772 ×1

Supports, Girders and Cranes 1 piece

Hook with Towball Dark Bluish Gray Part 30395 Element 30395199 or 6347464 ×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.

Request a replacement from LEGO

Buy the piece

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.

LEGO Missing Piece Checker

42108 Mobile Crane

Before you call it missing

Your missing list

Piece checklist

Technic Pins 482 pieces

Technic Connectors 223 pieces

Technic Beams 220 pieces

Technic Axles 128 pieces