PM-100 with a low negitive rail.

[Zenwizard]

So I got a voltek PM100 from an auction site that we all know and love. And it has an issue of course. When I start it up it only goes to current over range. This appears to be a power supply issue as it started working after about 20 minutes of on time. I have confirmed that the tl072’s are not getting enough power on the negative rail it is down around a volt when compared to the positive rail. Does anyone know how the isolated power supply works in this thing? Or do I need to start hunting with a curve tracer. It has worked on my bench but stopped working but I suspect it is leaky electrolytics.