My 1988 560SL (156K) had a new alternator installed 3 months ago after going haywire (dials erratic, systems shutting down one by one). All went well for 3 months, then the car went dead/wouldn't jump. Diagnosis: bad alternator ("this happens"). Four days after the new alternator was installed, I found the dome lights on, not responding to the switch, so I took the bulbs out. The next day, the dome lights, clock, radio, glove box light, and trunk light didn't work. Back to the shop. No diagnosis, but one dome light was replaced and everything seemed to work. Next day, the dome lights were on, but did turn off with their switch; however, the clock had lost 15 minutes. This problem is not fixed; it's just a matter of time before something else pops up.

Any ideas? Up until now this car has been great, just routine and age-related repairs.