Hello and asking for help with HP 67 power unit

[Tapti]

Hello Tony and all others,
my calculator found the way back to me without any further damage. Yesterday I tested it with the original wall plug. Unfortunatly the same thing is happening after some minutes, begining with faulty calculations and ending up with a dead display. What I can say in addition, it doesn't seem to be a temperature problem or anything else hinting towards an electric short. My impression is rather it might be connected to some charge accumulation somewhere, because the cure is just to switch it of for some more minutes. And so letting the charge to decay. The point is, I already took the piece apart for repairing the card reader but I never put hands on the electronic componenets as on the power supply or even on the logic electronics. I'm asking whether there may be someone under you guys, who perhaps could try to find the problem and evenrually repaire it. Perhaps somebody from Germany ?
Thanks a lot,
Stefan