Mercedes Forum - Mercedes Benz Enthusiast Forums - 1982 240D Issues...Need Some Help

thanks in advance for any leg up you might be able to provide....

I have several issues with my 240D sedan...it's no wonder as it's 35 years old....lol

1) turn knob below instrument cluster that controls cluster lighting brightness and which one pushes in to reset odometer is no longer working...it appears to have worn out and/or become detached from its base inside the console.....is there a quick fix/part replacement that will fix this problem?

2) fixed "vacuum" leaks several years ago....these have returned....car locking mechanisms not working properly from master control regulator (recently replaced) inside driver side front door...also engine fails to shut off immediately when ignition is turned off with key...need to depress clutch in order to shut down engine...any ideas on where to look for the problem?

3) have a short somewhere in the electrical system...this manifests itself now with the "reverse" tail lights not lighting up when car is put in reverse....also have one broken license tag light fixture which I have ordered to replace the old one....awaiting the part....does this signify "where" it might be that the short can be found without going through the entire electrical system?

I love my car but it is a constant battle to keep up with the repairs that crop up on this old darling....any guidance would be most appreciated...thanks.