Hi, I have a Technics SA-DX 1050 amplifier from 2001. When I hit test mode, all the speakers output noise normally. However when I connect TV/ DVD/ phone into any of the inputs, sound comes only from the left speaker. If I put the volume up to high, I can hear noise coming from the right speaker but it's not music. It seems like the amp is not picking up the right input, but for either multiple or all sources. Please does anyone know what's wrong, or how to fix this?