My home-theater system consists of a Sony STR-DB940 A/V receiver with 5.1 speaker setup, Sony KDL-52HX909 LED/LCD TV, Dish Network HDTV receiver, and Sony SLV-N71 Hi-Fi VCR. I have the VCR connected to the TV via composite video and L/R analog audio cables and the TV's audio output connected to the AVR via optical cabling (MD/DAT input). I have the Dish receiver's video connected to the TV via HDMI and its audio connected to the A/V receiver via optical (SAT/TV input). All of this worked great for about nine months until a few weeks ago.
The AVR's SAT/TV input works fine, but when I use the MD/DAT input for watching the TV or VCR, the sound only comes out of the left-front speaker. When I record something via the VCR's line in, the playback has the same audio problem. But when I play a tape recorded over a year ago, the sound does not have the audio problem.