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 Axle 5.5 with Stop [Rounded Short End]Dark Bluish GrayPart 59426Element 4508553×1
Technic Beam 1 x 2 with Ball Joint AngledDark Bluish GrayPart 50923Element 4503381 or 4289258×1
Technic Pin 3/4Dark Bluish GrayPart 32002Element 32002199 or 42110501 spare in the box×2
Trans-Orange
4 pieces
Projectile, Large Figure Weapon, Zamor Sphere / BallTrans-OrangePart 54821Element 4297030×4
Blue
3 pieces
Technic Axle Pin with Friction Ridges LengthwiseBluePart 43093Element 4309323 or 4206482×3
Pearl Light Gray
3 pieces
Large Figure Weapon, Claw, Triple, with 2 Pin HolesPearl Light GrayPart 56160Element 4494055 or 4293807×2
Large Figure Weapon, Zamor Sphere LauncherPearl Light GrayPart 54271Element 4494490 or 4288100×1
Lime
1 piece
Large Figure Head (Toa Inika) with Marbled White PatternLimePart 53558pat0001Element 4498706 or 4492471×1
Trans-Red
1 piece
Bar 4L (Lightsaber Blade / Wand)Trans-RedPart 30374Element 6507880 or 6167284×1
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.