ground fault after installing metal conduit?

I’m not going to do that, it is dangerous.

It is more than likely the switch, or the wires that connects it to the terminals. I will have to investigate it further.

Not dangerous. You would basically be reproducing what you suspect may be happening anyway. I would just replace the pull station and not bother with any of this and see where you stand.

Would never hurt to pick up a generic toggle switch, go to Lowes, Home Depot, Radio Shack, etc…, bring your old toggle switch as a sample and pick up a new one. A generic toggle switch costs around $3.

Would it fit into the pull handle properly? I’m not going to do anything with it just yet.

Bring the old switch with you when you purchase a new switch. Most toggle switches are a standard size.