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.
Technic Pin Long with Friction Ridges Lengthwise and Stop Bush [3 Lateral Holes, Big Pin Hole]RedPart 32054Element 4140806 or 4125198×6
Trans-Dark Blue
13 pieces
Cone 1 x 1 [No Top Groove]Trans-Dark BluePart 4589Element 618843×9
Plate Round 1 x 1 with Solid StudTrans-Dark BluePart 6141Element 6514055 or 62402142 spares in the box×4
Pearl Light Gray
10 pieces
Arm Mechanical with Clip [Thin Support]Pearl Light GrayPart 53989Element 4494600 or 4288114×8
Plate Special 1 x 4 with Angled TubesPearl Light GrayPart 61072Element 4518406×2
Lime
4 pieces
Animal Body Part / Plant, Tail / Claw / Horn / Branch / Tentacle, End SectionLimePart 40379Element 6293393 or 6172469×2
Plate 1 x 4LimePart 3710Element 4187743 or 4122441×2
Trans-Orange
3 pieces
Brick Sloped 30° 1 x 1 x 2/3 (Cheese Slope)Trans-OrangePart 54200Element 6245265 or 42443691 spare in the box×1
Windscreen 6 x 4 x 2 Wedge CurvedTrans-OrangePart 41883Element 4505858×1
Windscreen 8 x 6 x 2 CurvedTrans-OrangePart 41751Element 4525915×1
Tan
2 pieces
Technic Gear 20 Tooth Double Bevel with Axle Hole Type 2 [X Opening]TanPart 32269Element 4514555×2
Trans-Clear
2 pieces
Box 2 x 2 x 2 Door with SlotTrans-ClearPart 4346Element 6499105 or 6247357×1
Panel 1 x 2 x 1 [Square Corners]Trans-ClearPart 4865aElement 4113106×1
[No Color/Any Color]
2 pieces
Sticker Sheet 1 for Set 7645-1[No Color/Any Color]Part 63092Element 4527610×1
Sticker Sheet 2 for Set 7645-1[No Color/Any Color]Part 63495Element 4529044×1
Minifigures
6 figures
Mars Astronaut, Smirk / ScaredMinifigure, checked as a whole figure×1
Martian, Alien CommanderMinifigure, checked as a whole figure×1
MartianMinifigure, checked as a whole figure×2
Mars Astronaut, Cheek LinesMinifigure, checked as a whole figure×1
Mars Astronaut, Orange Sunglasses, StubbleMinifigure, 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.