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.
970 pieces in 281 part and color combinations, plus 7 minifigures.
LEGO counts 1,016 pieces. This inventory comes from a separate parts catalog and lists 1,017, including the 47 parts inside the minifigures; 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.
Plate Round 2 x 2 with Rounded Bottom [Boat Stud]White ×3Trans-Clear ×1Trans-Clear is see-through: hold the piece up to a light.
Brick Sloped 45° 2 x 1 with 2/3 Cutout [New Version]Black ×2Dark Bluish Gray ×8Black is darker than Dark Bluish Gray.
Brick Special 1 x 1 with Clip Vertical [Open O Clip, Hollow Stud]Black ×2Dark Bluish Gray ×2Black is darker than Dark Bluish Gray.
Plate Special 1 x 1 with Clip Vertical [Thick Open O Clip]Black ×12Dark Bluish Gray ×6Black is darker than Dark Bluish Gray.
Plate Special 1 x 2 with 1 Stud with Groove and Inside Stud Holder (Jumper)Black ×4Dark Bluish Gray ×6Black is darker than Dark Bluish Gray.
Technic Axle and Pin Connector Angled #5 - 112.5°Black ×4Dark Bluish Gray ×4Black is darker than Dark Bluish Gray.
Weapon Sword / Katana / Shamshir with Capped Pommel [Square Guard]Flat SilverPart 21459Element 61165931 spare in the box×2
Weapon Sword / MacheteFlat SilverPart 29109Element 6483955 or 61774181 spare in the box×1
Dark Brown
5 pieces
Pneumatic Hose Connector with Axle ConnectorDark BrownPart 99021Element 6265670 or 6167942×3
Weapon Lightsaber Hilt with Bottom RingDark BrownPart 64567Element 61338321 spare in the box×2
Pearl Titanium
5 pieces
Weapon Lightsaber Hilt with Bottom RingPearl TitaniumPart 64567Element 61227271 spare in the box×2
Weapon SaiPearl TitaniumPart 98139Element 6270137 or 46468701 spare in the box×2
Weapon Sword, Big Blade with BarPearl TitaniumPart 98137Element 6270134 or 6171010×1
Tan
4 pieces
Technic Pin Long without Friction RidgesTanPart 32556×4
Red
2 pieces
Technic Axle 4RedPart 3705Element 6129995 or 4265797×1
Technic Rubber Belt Medium [24mm ID] [Round Cross Section]RedPart 85544Element 4544145 or 4544143×1
Sand Green
2 pieces
Brick Special 1 x 1 with Studs on 2 Adjacent SidesSand GreenPart 26604Element 6223225×2
[No Color/Any Color]
2 pieces
Game Board, Ninjago: Master of the Mountain[No Color/Any Color]Part 6325698Element 6325698×1
Sticker Sheet for Set 71721-1[No Color/Any Color]Part 67959Element 6300565×1
Bright Green
1 piece
Plate Round 2 x 2 with Axle Hole Type 1 (+ Opening)Bright GreenPart 4032aElement 6138624 or 4114430×1
Dark Orange
1 piece
Brick 2 x 2 CornerDark OrangePart 2357Element 6253417 or 4164442×1
Dark Turquoise
1 piece
Brick and Axle Separator v2.0Dark TurquoisePart 96874Element 6254100×1
Trans-Clear
1 piece
Plate Round 2 x 2 with Rounded Bottom [Boat Stud]Trans-ClearPart 2654Element 6581772 or 6163901Also in White×1
Trans-Dark Blue
1 piece
Rock 1 x 1 Crystal 5 PointTrans-Dark BluePart 30385Element 6507864 or 6236962×1
Yellowish Green
1 piece
Minifig Head Special, Skull with Black Eyes, Mouth with White FangsYellowish GreenPart 43693pr0005Element 6290493×1
Minifigures
7 figures
Nya / Hero NyaMinifigure, checked as a whole figure×1
Kai / Hero KaiMinifigure, checked as a whole figure×1
Awakened WarriorMinifigure, checked as a whole figure×2
Skull SorcererMinifigure, checked as a whole figure×1
Statue - Lilly Light Bluish Gray Hair in BunMinifigure, checked as a whole figure×1
Jay / Hero JayMinifigure, 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.