[WaveyDipole]

Originally Posted by OldTechFan96

I do have some more BF199s so I'll try changing one later. I'll remember to take measurements with the timebase stopped.

Voltages on the input of R363:

Hor. ext. in: 3.38V

Hor. ext. out: 3.22V

IC pin 4: -871V

C of T353: -872V

Let us know how you got on with swapping the BF199.

Thanks also for those readings. However, if, in addition to the above if you could provide the voltage readings for those same points with the timebase stopped as suggested by wme_bill, then that should be helpful.