Electrical problem
1985 Mercedes Benz 500sec V8 Two Wheel Drive Automatic 130000 miles

turning it on is no problem but the key will just be stuck and not turn off, playing with it doesn't help. it seems as if at of nowhere and suddenly it magically turns and I can finally walk away.

I had a new original tumbler install just a week ago. I talked to the locksmith and he tells me it is the wiring. what should i do. I was actually about to sell the car :/ please help