Hi all, Please excuse the odd thread title.  I have a Peavey T-Max from around 2000.  Just before the first lockdown, the amp made a low rumbling sound when switched on, kind of like static-y thunder noises.  No signal would pass through and preamp/volume settings didn't make any difference.  After switching off and on over a period of time, it never worked right and always made the same noise. Fast forward a few weeks, I had a tech look at it who said he could find nothing wrong with