Submitted by owner on
Two Lego Duplo locomotives (5135cx1, from sets 3771, 3772, 5608, 5609) stopped working after several years of non-use. The problem in both was the same: a broken plastic pinion. A replacement can be obtained, even in metal (brass), for example, from the Polish company KK Produkcja on eBay.
The pinion is a gear wheel with parameters: M0.4, 9 teeth, D4.8, L5, B1.95.
The procedure for disassembling the locomotive chassis is shown in the video.
Remove two screws from the battery cover.
Remove two screws from the battery cover.
Remove three screws from the chassis cover.
Carefully loosen the front part with some blades/the opposite side of the tweezers.
The challenge is to release the latches at the back.
Use tweezers to release the plastic holders of the PCB from the drive block.
By gently gripping with all-purpose wrench, you can pull off the rear wheel on the opposite side to the pinion.
Loosen four screws of the drive system structure.
Remove the broken plastic pinion and replace it with a new one.
Reassemble the drive system structure. The pinion fits perfectly into the gear.
When handling the PCB, the power cables might come loose. For repair, a micro-soldering iron and soldering tin are needed.
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