Hi Mitch,
An usual “sausage frying and crackling” noise is a result of a bad preamp valves, especially first tube. Louder crackling and popping noise can be associated with bed soldering connections on the preamp tube sockets.
Overtoe is well build amp, especially older ones (serial production can affect quality unfortunately).
If you moded an amp check the connections again and all capacitors you’ve changed.
Good luck with the tests and I’m glad you enjoying a snake skin custom cab