W124/M104: Fluctuating speedometer needle & Visor light
 

The speedometer needle in my E320 fluctuates up to about 30 mph. One mechanic suggested to replace the speedometer cable, another one the speedometer itself. Any experiences?

Also, the passenger visor's light is out, and on this one both agree that the whole visor must be replaced! Wondering if any of you has successfully managed to open it and change the bulb nevertheless...

It could be either. My it probably the cable. My mom's acted that way then gave out. I changed it and it's back to normal. I'd try that first since it's probably cheaper than changing the speedometer itself.

Passenger visor's light is out on mine too. I'm not even going to bother with it. It's not that important. If you really want to fix it, you should be able to pry out the mirror then replace the bulb. But when you put the mirror back in, you'll have to use some adhesive. Someone tried it in my car (I'm the 2nd owner) and it's falling out.

Kinked or binding speedo cables will result in the symptoms you described.

Sometimes lubing the cable will fix the problem, but most likely, the cable has already seen damage and the lubing will only be a temporary fix.

A replacement cable is the cure.