The vibration isolators are there, but one of them also has an integral jumper that allows the attaching bolt to get a ground. They're notorious for getting a little rust or corrosion at that connection. Then the regulator can't function properly. The ground wire was usually attached directly to the regulator base with a small sheet metal screw if one was used.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!