I have to tell you- I've had that same problem with the AMP light with two of the cars I have. My 164E had that problem and I found that the wiring that goes from the alternator to the regulator was loose. Now it has to be pretty tight in order for it to work properly. If it is loose, then you'll get some arcing and a lousy connection. But with your car (seeing as I have owned one just like yours!) it sounds like the regulator has gone out. With that year, the regulator was NOT built in with the alternator, so you have a nice and easy regulator box to replace. I replaced mine for under 40 dollars. It's easy too! You just remove the wiring harness (it only plugs in one way) and unscrew two screws, put the new regulator in place and plug in the harness. That should solve your problem. If not, then I'd check all the connections coming from your alternator going toward your regulator. If that doesn't help, you can email me. I've got a million other things you can do....

-Raymond :)