Buzzing sound from voltage regulator

[variant]

I can hear an intermittent light buzzing sound coming from the voltage regulator on my '69 Notch when cruising on the highway. It is only there when the car has been cruising at high rpm for a few minutes and goes away when the engine rpm drops off. AFAIK this is the car's original VR, p/n 113 903 803 E. The generator is good - received new bearings & brushes 6000mi ago and the commutator was cleaned up in the lathe at the same time. Belt tension is also good. I get 13.8V at the battery with the engine turning at about 2500 rpm.

I have another VR of the same type but I am a bit reluctant to try it as the condition is unknown and I have read plenty horror stories of generators being burned out by faulty VRs.

Can these VR's be opened and cleaned/adjusted, should I just leave well enough alone or should I rather fit a new Bosch electronic VR? Has anyone had any particularly good/bad experiences with them?

Thanks in advance.

[Speedstah Guy]

Essentially, your VR is operating as it should. It may, because of age, be a bit loud - especially at highway speeds as the battery reaches full charge - because then the relays are reaching their operating threshold and opening/closing very rapidly as they work to maintain 13.8 volts and no higher and THAT is the buzzing that you hear. Sometimes the buzzing (which is the relays vibrating the tin housing) can be reduced by tightening the VR assembly to the mounting surface, tightening the tin cover to the VR base or using some dynamat on the outside of the tin to dampen the vibration a bit, but the best way is to simply install a newer VR and see if that helps.