I think i know what you mean about the channel off feature. tried changing channels manually and no luck. It just shut off while I was watching it, didnt change channel or anything. Not sure where to go from here.
I tryed tapping it on the side too, sounds weird but the 81 set i had growing up would be working fine, and would shut off the same way, with a bit of a staticky sound from the screen, but would always come back on if you whacked it on the side
it worked that way for years, always wondered what caused it. lol
Another question would be, does anyone know a tv tech around minnesota/ north dakota that still works on these?