electrical problem - signals and brake

[mattn]

A while back the turn signals and brake lights stopped working on my 72 911 (86 engine and transmission). I am NOT an electrician, but I found a loose wire leading into the top fuse which handles those lights. I tightened it up and the problem was fixed. It happened again a short while later, but the screw is tight.

What is strange is when the engine is off, the turn signal lights come on and stay on when the signal switch is engaged. It has always done this when I accidently leave the signals on and stop the engine. I assume this normal. And it means the lights are getting power, bulbs are good, etc.

But when the engine is running the signals don't work. I wasn't able to check the brake lights since I was alone this morning but I think they have the same problem.

Automobile wiring is a mystery to me but I hate to pay someone to fix something that seems alot like a loose wire somewhere.

I would appreciate any advice. (yes the fuse is good.)
Matt