"it's not unusual to find voltage present in disconnected wires run in parallel with wires that are connected to a voltage source"

I agree but in my experience the voltage that you are talking about that is present is so minimal that's it's pretty easy to tell it's not a true read. just my thought. Not sure about replacing just the diodes in a regulator... you would have to break thru a pretty rubbery substance to get to the inside on the regulator, to the diodes, then replace it with something, not sure I would want to do all that and take a long road trip with it. I say change it, and be done. For sure this has been a learning experience, sure hope it helps someone else that might run across the same problem.

 

I am pretty sure the regulator is non-serviceable since it's potted (immersed in a rubber-like semi-solid). Worse thing we do is to put a chrome cover around the regulator. It needs all the air it can get. It dumps the excess current to ground and generates a lot of heat.

 

first check battery connections clean and tight at both ends.
then check battery condition. Could have a bad cell or plate.
then check the main circuit breaker under the seat in front of battery.
Then diconnect the voltage regulator plug from the stator.
Use a multimeter on ohms (digital preferred) across oth stator leads, should read continuity, then from either lead to case ground. Should read full open.
If you don't get the above on either test you have a bad stator.
These would be starting points.

 

And that is why you wont see a cover on mine.