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.

Monorail Stop / Reverse Switch

Checking

5039 Monorail Stop / Reverse Switch

3 pieces in 3 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.

Show

Piece checklist

Light Gray 3 pieces

  • Brick Round 2 x 2 with Axle Hole Light Gray Part 3941 Element 614302 or 394102 ×1
  • Tile Round 2 x 2 with Yellow Arrow with Black Border Print Light Gray Part 4150pr0016 ×1
  • Vehicle Track, Monorail Monoswitch Light Gray Part 2774 ×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.