Hello,
I would try to change components further up the chain. Or turn those on cold with the amps and then turn the preamp on first. You are supposed to turn on source- preamp- then amp. When you shut down you should turn off on the order Amp- Preamp- and finally sources.
In the Chicagoland area I use this company called Deltronics to check out / repair gear. The tested an amp I bought on eBay which they can run on a Variac first to check it out. They rebuilt the motor board on my Linn Axis TT, plus a few other things. Take it to an expert. They charge $50 to check it out. If it needs more they tell you.
Also, Start with the manufacture. I hope this helps