Would be nice if one or the other could be programmed to a different code. Short of that you probably have the right idea, and just need to find the receiver. Sounds like you have a pretty good handle on it already. If you open it up and still can't figure out what is what the next thing I guess would be find something able to block the IR completely, like aluminum foil maybe? Wrap it and confirm no signal. Then poke a hole, and move the hole around until you locate find the perp.
Actually now that I think about it this is a lot of trouble. Maybe just get a turntable? No one ever has remote control problems with their turntable.
Actually now that I think about it this is a lot of trouble. Maybe just get a turntable? No one ever has remote control problems with their turntable.