I know, real engineers and techs don't need schematics, but it would make this a lot easier. :)
It's a linear power supply with OVP and the OVP isn't working. Now, that sounds pretty simple - a pot and zener and SCR. But it's not quite that simple and it may be that someone (like me) repaired this many years ago and didn't put correct parts in. In fact, that may be the only problem!
Google finds a manual for the dual version, but they are sufficiently different as to make that less than entirely useful. And this model is not listed on the Elgar/Sorensen Web site.
Thanks!