Defective Nikon FM2 Hot Shoe

Well my favorite slr seems to have a dysfunctional shoe mount. There is no signal being sent to my external flash, which works fine on my OM1 btw.

I tried cleaning the contacts with alcohol but no luck. It was working a few months ago, but something has happened.

How do I fix this?

Does the flash work through the PC socket? If it does, I think either broken wire from PC to hot shoe or possibility the safety switch isn't working.
The safety switch is part of the hot shoe and is opened when the flash is slid into the shoe.
The switch is under the tension spring in the shoe. Remove the spring and check that there's a plastic pin under it. This pin is pushed down when the flash is inserted. If the pin's there, the problem's under the cover.