I have my 5 years old Sony AVR having problem with the center channel before, the sound comes and go and with noises in between or totally no sound.
I got mad and bang on it, and the sound came back....before I sold it off, I ask my neighbor who is an electrician to check out for me, and when he return the Sony to me, he told me that, it's the dust that's causing the problem, use a small blower or vacuum cleaner to blow/suck away the dust solved the problem. he just clean the interior and the AVR sounded as good as new.
I've told the same to some of people here when they have the "no sound" problem...they clean it, and it does fixed the problem.
Maybe the dust in the 3808 connector just fell off so it worked again.
anyway, good luck on your 4310..it's a nice AVR.
