A friend knows I like to work on vintage stereo equipment and asked me to look at his SX-680s and tell him whether it's something simple like a switch. They both power up, neither has any output. One lost both channels at once, the other he continued to play with one channel until it also died. He had one since new, it is in very good cosmetic condition. The other has a lot of peeling "wood" but is otherwise good. As it appears that the only common failure mode on these (if powering up okay and fuses are all (4) good) is bad 039 modules, should I just tell him to dump them? Seems that proper modules and repairs will be more than a good running one is worth today. Thoughts?