The "relay coil" is actually called a cutout relay, directly behind the Bat terminal of the regulator. It's basically a magnetic on/off switch that connects/disconnects the battery and the generator to prevent discharging the battery when the engine shuts down. If the ammeter is showing any movement in the + direction with the engine running, the cutout is working. The points can get dirty, but that just reduces the amount of charge getting to the battery.
The control you probably need to be concerned with is the "voltage regulator" behind the FLD terminal of the regulator assembly. Increasing the spring tension on that set of points raises the voltage available to charge the battery. If those points get stuck or the field wire gets shorted to ground, the voltage will rise too high, resulting in an overcharged battery. Do the cruise-RPM voltage test before you start shotgunning parts at the job- - - -a simple cleaning and adjustment of the V/R points might be all that's needed. Don't use sandpaper or a file on the points- - - -they meet with a slight wiping action and sanding scratches can make them stick. A clean piece of a business card or an index card passed between the points should be sufficient to clean up any oxidation.
Jerry
