Hi, i recapped and restored my HK6500. I run only the power amplifier board, i eliminated all the other boards for now, they have their own problems. There is a little of parasitic hum in the speakers, i have tried to solve it but ran out of ideas. I replaced filter caps and reflown 75% of the board to eliminate grounding issues. The hum is still there. It's got some volume when i turn it on, then it gets quieter, but as the amp heats up (let it running overnight), it gets back to the original volume. Its audible only from very close to the speakers. The other issue is that the Lch DC offset jumps to 20mV no matter what i do. I nailed down right channel at under 9mV. To go with that, the heatshrink tied BJTs in Lch and NPN driver transistor (2SC3298) run hotter than their Rch counterparts. I am really keen on saving this amp, appreciate any help!