Denon DRA 345R problem

Greetings to all. I have just inherited a Denon DRA 345 receiver. It is in mint condition but there seems to be a problem with the output power. When playing with any of the source inputs as well as the tuner the right channel is inaudible unless the balance dial is set at the position just before it slides into "full right". In this position both right and left are pretty much equal, only if the right speaker is hooked up to the "B" speaker side. Not so lucky on the "A" side. I would like to get this working properly if I can. Is it worth trying to repair?
Thank you for time and replies.