I was getting F61s consistently on my Panasonic SA HT70 model with the power on off clicking noise. What seems to have resolved it for now is 1. unplugging power cord, 2 wait five minutes to let residual power dissapate from unit, 3. use electronic contact cleaner with thin red spray tube and spray inside each input/ouput jack in back, 4. clean each patch cord lead. 5. do same for speaker output connectors. 6. for laughs I did same to AM/FM antenna outputs. The contact cleaner has high flash and evaporates quickly. Repeated above with compressed air in can with same red tube. No problems since.
Keith
March 2006