I have an old Philips 2-channel receiver (7831). I have been using it for about 2 months now with my RTi4's, with no problems, except I had to clean the contacts. Now all of a sudden my left speaker sounds real fuzzy, barely plays, but the right plays perfecctly. It isn't the speakers, as I switched the speaker wires, and then the left plays fine with the right side speaker wires. Is the internal amp in my receiver blown? Should I take my receiver to a shop to get it looked at, or is it time to retire my old receiver and get a newer one?