Well, I managed to solve my bit noise issue in the right channel of my H3500. I carefully unseated each socketed IC and brushed off the pins with some Gold DeOxit and carefully reseated, making sure that no pins were bent underneath the chip upon insertion. I did find one IC in the attached photo (yellow circle) that had a pin bent underneath it that wasn’t making contact. I don’t know the function of this IC but it could have been the culprit in the bit noise I was experiencing….or not. It could have also been the IC pin cleaning job. Not sure, but either way, I have clean IC pins and a 100% noise and trouble free H3500 now!
Caution, if you don’t know how to pull and reseat delicate ICs properly, watch a decent YouTube video on it first before undertaking the endeavor because you can damage some pretty hard to find chips if you don’t know what you’re doing. A cheap IC extraction tool or two from Amazon will save you lots of headaches.