I left my mechanical hacksaw running while my back was turned. I came back to find it had stopped.

There was a cutting which might have caught in the reciprocating arm.

The 13 amp fuse at the plug had blown. When I replaced it, it just blew again.

I checked the on/off switch wiring/operation it was ok as was the wiring at the junction box.

There is what might be a red reset button on the bottom of the motor. It doesn’t seem to work.

What should I look at next?

Google for the pdf?

Hire a Stihl saw?

Google for the pdf?

It must be thirty years old. I doubt there would be a pdf for it. I’ll have a look anyway

It must be thirty years old. I doubt there would be a pdf for it. I’ll have a look anyway

Maybe?

If it’s blowing immediately, I’d suspect some sort of short somewhere.

Anything look like it’s melted / broken off?
Cable scorched / melted?

What resistance readings do you get for the coils.

Single phase or three phase.?

The fact the fuse is blowing instantly suggests a short somewhere.

I’m going for an earth fault, overheated motor broken the insulation down and knackered it, (so basically a short circuit to earth). If there’s no obvious other short, take the motor to a rewind shop and get them to do a winding resistance test, (Megger test).

Thanks folks, I’ll do some more tests on the wiring.

In the meantime, a mug of tea later and it’s cooled down and running again. I suspect the pipe I’m cutting through may be overheating the motor.

Thermal protection I bet. Most motors have some kind built in, I’d expect a bi-metallic “klixon” type on something that old. Be warned; once they have gone, they are prone to go again, then it’s motor rewind time!