I'm gonna have to give a strong second on SR's and KM's recommendations here....
A few weeks ago, I pulled the 6-pin connector off of the R/R, to make sure the dielectric grease there was holding up ok.
In the process, I worked the connector back on and off several times, and also regreased it.
I also pulled the connectors out of the rear of the junction box, inspected them for cleanliness, and reattached them.
Since then, I've noticed stronger voltmeter readings--especially at lower rpm's.
If this sort of preventive maintenance will work for a "younger" bike like mine (a 2005 model), think what it could do for an even older VN750....
So KM and SR are indeed right...apparently we need to modify the bike's "official" maintenance schedule to read something like, "once a year, inspect/clean/grease (dielectric)/tighten all electrical connections and battery terminals/frame grounding."
For many folks here, it might be a good idea to work the above during the non-riding (winter) season, when the bike is otherwise in storage and precious riding time isn't otherwise wasted turning screws/wrenches and dabbing grease.
In any case, be sure to use a cleaner for the above that is formulated for cleaning electronics--it MUST
specify on the cleaner's container that it is safe for plastics
Heck, this bit of TLC might even cut into the stator and R/R failure rate.....