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.

Transformer / Controller 12V

Checking

7864 Transformer / Controller 12V

34 pieces in 20 part and color combinations.

LEGO counts 33 pieces. This inventory comes from a separate parts catalog and lists 34; 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.

Show

Piece checklist

Black 21 pieces

  • Brick 1 x 8 Black Part 3008 Element 300826 ×2
  • Brick 2 x 4 Black Part 3001 Element 300126 ×2
  • Brick Round 2 x 2 with Axle Hole Black Part 3941 Element 614376 or 614326 ×4
  • Brick Sloped 45° 2 x 3 Black Part 3038 Element 303826 ×4
  • Control Switch, Train 12V Transformer Speed Throttle Black Part upn0260 ×1
  • Plate 1 x 6 Black Part 3666 Element 366626 ×1
  • Plate 4 x 6 Black Part 3032 Element 303226 ×1
  • Technic Axle 2 Black Part 3704 Element 370426 ×1
  • Technic Axle 6 Black Part 3706 Element 370626 ×1
  • Technic Axle 8 Black Part 3707 Element 370726 ×1
  • Technic Brick 1 x 4 [3 Pin Holes] Black Part 3701 Element 370126 ×2
  • Technic Plate 2 x 8 [7 Holes] Black Part 3738 Element 373826 ×1

Light Gray 12 pieces

  • Electric Adapter / Transformer, Train 12V, 220V Type 1 Light Gray Part 7864c01 ×1
  • Electric Connector, 1 Way Male Squared [Complete Assembly] Light Gray Part 765c01 ×4
  • Plate 2 x 4 Light Gray Part 3020 Element 302002 ×2
  • Technic Bush Light Gray Part 3713 Element 4125313 or 659002 ×2
  • Technic Gear 24 Tooth Crown with Flat Teeth Light Gray Part 3650a ×1
  • Technic Gear 24 Tooth [Old Style - Three axle holes] Light Gray Part 3648a ×1
  • Wire 12V / 4.5V with Two Leads [Undetermined Length] Light Gray Part 74503 ×1

[No Color/Any Color] 1 piece

  • User Guide, Information Note for Parents, 12V Transformer - 108681 [No Color/Any Color] Part 108681 ×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.