Thanks Paul for the detailed instructions, really appreciate.

I was going to do these tests, but before starting I tried to slightly tap the chips of the AD/DA section to see if  some oxidation in the slots was maybe giving the problems. Turning it back on, with surprise, my Polaris is now sounding same as my chainsaw! :( What I only hear now, is a loud modem-like digital sound.

Before writing back to you with new problems, I tried to see what happens but cannot find anything wrong.

Thanks so much for your patience and help!