I just purchased a 1986 500SEL euro model with 43,000 miles on it. The car has rarely been driven in the last 10 years. It seems to run perfectly but I really know nothing about these cars. I haven no maintenance records so I am wondering what I need to look for maintenance wise? I have heard that I should have the timing chain and guide replaced as a precaution. Is there anyway to tell if that is in fact the case? The car idles at around 750rpm.

Also are there any good DIY sites for repairing the following:
1. the sunroof seems to be off track
2. the back right lock does not work
3. the aftermarket Alpine stereo turns on but produces no sound

Thanks!