Great points WD.
The Ch2 of the Scope is not reading DC at all, but it displays sine waves from the FG when set to AC but only above 100 Khz.
As you say, I am not sure if it is dirty contact on the Voltage selection switch, or if it is more serious such as blown FET, diodes or Transistors, or even burnt out resistors or dried out Capacitors.
I would think it would be straight forward process of checking every suspect components one by one on CH2 PCB, and compare them with the ones on the CH1 PCB, and if there are noticeable differences in values, or bad components, then I would know what to replace. But it would be much time and effort consuming process I would reckon.
Another point is, although the scope seems operating OK on AC, I am not sure if it is working 100% accurately either. I could compare it with other scopes on this issue, but they are all very old vintage scopes which dont give much trust. For that, I would need a FG and scope which work perfect, and then compare properly all the aspects of the operation of the devices?
Yes, I will open up the FG2001 and try to apply the Maplin switch cleaner in the pots of the freq. selection buttons first, and see if it will improve things.