Then it might be a power supply issue?

Check the cables to the fan with a multimeter or such while jiggling them around. It may be a break somewhere in the leads that makes contact on and off as the carriage moves around.

You may also want to have a look and inspect the motherboard. Have a good look at the connectors and leads, and look out for any signs of scorching. Also check the specs of the power supply unit (the brick thing).