i disconnected the wiring plug from the motor and the fuse doesn't blow so its def a motor problemI have had to do a couple around that age and the wiper spindle drive had seized up, and in turn overloading the motor. They are driven by a cable from the motor behind the passenger side dash.
It's a real pain of a job so you want to be sure it is that before you start.
had it on mine was wiper spindle seized they are about £7on e-bay.
duuno what your dash is like but i took top bit off mine dropped instrument panel forward and did it that way about 3hrs.