[suicideneil]

Well, using a 1/10 motor in a 1/8 vehicle is a recipe for disaster- 1/8 vehicle needs 1/8 motor.

The esc itself will be fine with running a smaller motor and lower voltage, but the motor will most likely burn up if you put it in a 1/8 vehicle and try to gear it for any kind of speed (over 20mph say).

Dont do it in other words- you can happily use a 1/8 scale motor in the high 2000kv range on 3s lipo, but a 4000kv item on 2s lipo is not going to work too well, especially since its under sized for the application.

As for your friend, yep, MMM is covered under 12 month warrenty for things like that. What I would suggest is once its fixed & returned, put a zip-tie around it to prevent the case popping open. There is a form on the castle website that needs printing out & filling in and sending in with the esc.