I had recently got my Lego 7730 for past Christmas and wanted to use it. I bought the Lego 7864 and went to test the red motor but all I heard was the motor and it didn't move. I decided to take a look inside to see what was up and found out that when electricity went to the motor, the motor would turn but the axles wouldn't. I looked at the axles and they were bad. Does anyone know how to fix or get new ones, cause I can't run my 7730 with bad axles, as they are stripped. Help me!!!!

  • It's going to be difficult to help without pictures of the problem area. Can you add a photo to your post?
    – jncraton
    Dec 9, 2016 at 17:58

1 Answer 1


It's difficult to answer definitively without a photo or video of the issue, but I'm not aware of a way to easily get replacement parts for this.

I'm sure you're already aware that you can buy a replacement motor on Bricklink, but that's going to set you back at least $100.

Internally, this motor drives a pair of gears on the axles using metal worm gears. One of the common issues with this part is that the metal worm gear slowly wears down the other gear until the there is a complete loss of contact and the motor spins freely without driving the train. It sounds like this may be what you are experiencing.

Here's a diagram of the internal components:

motor teardown

I'm not aware of a third party that provides replacement parts for this, and I'm sure that LEGO doesn't provide them anymore. One option could be to buy the somewhat cheaper black version of this motor and swap out the axles from there.

  • Thanks. I will put up a picture, and I'm looking into buying a old black 12v motor for very cheap. The owner says it doesn't work so if I can't get it to work, I will take the gears off the axles and put them on the red motor. The one question I have is, how did you get the wheels off the axle in the first place, without messing up the wheel? Dec 21, 2016 at 1:44
  • That's a great question about getting the wheels off of the axle. I don't personally have this part, so I can't say for sure. It may be very difficult to get these off. Hopefully someone else can offer a suggestion.
    – jncraton
    Dec 21, 2016 at 1:58

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