I gave my AU-7900 the deoxit treatment the other week but, similarly, failed to sort it's Phono 1 problem (both channels). Phono 2 works fine, but does not have the variable impedance switch which Phono 1 has. I checked a picture of your 7700, and it looks like it has that switch, too, so you could also try cleaning that switch on the inside (was easy to get to in 7900). It didn't work for me though :thumbsdn: