The voltage regulator only handles field current not output. I have seen VR potting liquify. It is from age not heat. Heck it can be 30 to 54yrs old.
Not totally agreeing with the age vs heat thing. I had a couple NOS ECU`s in a hot attic and they leaked out. I had others in the garage where it was cooler and they never leaked out.
How hot does your attic get? Certainly high heat can lead to premature break down of the potting. But I have seen plenty of ECU leak out stored in cool cabinets. So to imply as long as they don't get hot they will last is wrong.
In his case we are taking about electronic VR which only handles about 2.5amp of field current. Also the notion that loss of a ground cause this is not correct either. Losing VR ground means NO field current, and low no alternator output.
If it truly was "just" heat you would see a potting leak or hole in the vicinity of the power transistor that generates the heat. Yet plenty of ECU and VR to a lesser extent have all the potting go soft.
