I tore my amp apart and did some work on it, I did find a transistor cracked (my guess is someone overtorqued the mounting screw). I will replace it here soon, just need to get one in.
I did find some other issues with corrosion on the board. I did repairs as I could. Amp is well made, but the ends are open for airflow and the entry point for moisture from the side vents of the car in the back is my guess.
If anyone has an amp they want me to go thru, I can for a very reasonable charge. I am an RF Technician by trade and have all the best tools and 30 years experience from tube radios to cell phones (current job 16+ years experience in cellular) to multi-million dollar radar systems.
I would like to see more of these amps inside to see if there was a common problem with cracked transistors. I can replace them with new ones to fix the problem forever.