That's a tough one-phono stages are pretty simple in most receivers, so there is not much there to fail. Are you using a MM cartridge, and is it the same one that you were using previously when it worked? Most receivers will only work with MM carts-they don't have enough gain for MC carts (but you probably already knew that!). If you have a dBx decoder, you might want to make sure it is not engaged unless you are playing a dBx disk-I did that several times myself. You might want to look at the internal connections between the phono stage circuit and the RCA jacks-my old Yammie had some flakey circuit-card connectors (not on the phono stage) that were the main excuse for my subsequent purchase of my new Denon. It sounds like you already did a pretty methodical troubleshoot, so you might be having a 6 sigma experience (ie, low probability failure). Good luck.
