Generator indicator light
 

My 74 1.8 generator light will come on and the voltage will drop when the RPM,s reach 3500. When the RPM,s drop back down the light goes out and voltage returns to normal.Could this be a loose belt or the brushes jumping around at high RPM,s? The problem seems to be getting worse. HELP!

Check the belt first, it's fairly easy. To change it just pull the belt off the pulley while rolling the car forward in gear, to install, put it on the alt and half way on the fan and roll the car again. Obviously care must be taken to keeps ones fingers out of the way, and a friend to help push the car is a big help.

Next see that the Voltage Regulator is seated properly in its socket on the relay board.

After that look at the pelican parts tech article by Jim T. on starer and charging systems.