Hi Bert & Vincent,
I'll check capacity specs on the FET's as well -although already ordered :-) - but the good news in relation to the secondary power supply:
The scope has been running fine for several hours now on an external 43VDC :-)
I needed it to run, because it turned out there was a problem with CH1 as well. (trace yes, but no signal showing)
I cleaned the switches using IPA, but it looked like it was one of the small trimpots in the attenuator having a dodgy contact.
As soon as I touched that one the signal came back on CH1.
After all repairs are done I will calibrate it.
I updated the album to show the progress.
Thanks for the feedback, un saludo,
Leo
satbeginner