2002 pontiac grand prix radio problems

[thecrow1986]

its a 2002 grand prix gtp 3.8 supercharged with on star and bose. its still all original factory amp, deck, and speakers. problem I had first was every now and then I would hear a high pitched whining noise come over the speakers and then if I would shut it off and back on it goes away. but now the left door speaker is out but the tweeter works fine and the left rear speaker seems to be working maybe 10% outoput or maybe its just the smaller of the left rear working, the passanger side is fine. its not the fade or other n
knob tride that. any thoughts?