hifi engine

Anyone have time to answer a question about Luxman receiver problem?

I recently acquired a very clean Luxman r-115 receiver and it was working fine for a couple of days, then it started some hiccups. When a cd is playing and I switch source to FM, the cd still bleeds through. Also there is a "CD Direct" circuit that was working fine, but now when I switch to CD Direct, the left channel cuts out. When I listen through the regular CD source switch, everything is fine. My question is, can anyone lead me in the direction of where to begin to search for the problem. The receiver was recently Caig Deoxed, and is very clean. Thank you! -Mike