When I was having a mess of sporadic electrical issues, I got some "Ozone Hateful" electrical cleaner from my dad (builds his own Nuclear Systems computers)... So "Nuclear Grade" contact cleaner?

Took ALL the fuses out.

When underneath and sprayed liberally... Wear protection, that was MESSY

Wen on top and Sprayed even more.

Cleaned up all kinds of gook

... then I wrote off the fuse box as "not the problem" and gritted my teeth!

 

While we are on the fuse-box wiring problem. The '86 944 we have is having problems with the taillights...It seems the connection to the bottom of the fusebox may be corroded or screwed up. Reason being, I can bridge the rear-passenger side fuse to the rear-drivers side and get the drivers side to work. But, stand alone there is nothing across the drivers side fuse...I tried taking the fuse box out and the light comes on, but goes off as I put it back down...
I don't think my brother likes my solution, set the car on fire.
-Robert D.