Hi everybody. Question on my Sansui 881. Thanks to the experts here (dr. Audio) I was able to cure the low volume speaker hum by tightening the screws on the main board. However, I still have a problem sometimes when first powering on. I get a hum from the back of the receiver (not through speakers) which coincides with low volume output. After a few minutes hum goes away and volume returns to normal. Then unit works/sounds perfect. Is it a power supply issue? Everything else works perfectly, so I’d hate to damage it. Thoughts? Thanks for your input.