The right front speaker sound drops out intermittently as of about 6 months ago. Also the center channel just began lately. I can temporarily correct the problem by tapping on the speaker connection posts - or, lately have actually tied rubber bands around the tightening knobs of the connection posts to put inward pressure on them. This corrects the problem, but in a rather inelegant way This should be a no-brainer, right?- loose speaker post connection.... Not so. I have done everything I can imagine: solder terminal ends on the speaker wires, put di-electric grease on the terminals (sparingly) after brass brushing all surfaces of the connection post and tightening knob. I even broke off much of the plastic of the knobs to expose the metal contact area of the knob and post. Last I took off the receiver cover and disassembled the receiver to the point of inspecting the circuit board connections to the speaker posts. I saw no evidence of connection break. Just to make sure I re-soldered all connecting points on the circuit board involved with the speaker output to correct a potential invisible "cold-solder" problem. All of this has not solved the problem. Anyone got any ideas?