John Greenland
CVRS Member

I am not sure where the info for the model 208 cartridge comes from but what I found only lists the output at 750 millivolts.

I agree with Allistair to try one channel at a time to see what happens. According to the schematic for a Viking 48-74 the cartridge feeds into a series 1 meg resistor.
You may want to check it for value. It forms a divider with a 270 K which should be checked as well.
R27 and R28 on the schematic I am looking at.

Regards John G. VO1 CAT