The problem could be a bad earth, with an open circuit in the wiring loom, a live wire from the windscreen wiper getting in contact with earth and blowing the fuse intermittently. Check if that fuse is used only for windscreen wiper or other functions in the car could be used for the same fuse. Wiper stalk must be checked as well, could be short circuit. The other fault could be inside the wiper motor itself, internal fault, for example overheating, wiring, where it should be replaced itself, but best to get it in to an electrician garage as it could be one of these many things i just mentioned.

Regards,

Servicing Stop - Car Service Nationwide