Main Output Issue- Help

Since I don't have my MPC expanded to 8 outputs, I use my main outs to track my beats. Out of the blue whenever I switch one of my instruments to the R out I get no sound. This also happens when I pan and instrument to the right as well. Has anyone run into the same problem and how did you resolve it?

Do you get the same phenomenon from the headphone output?

If yes, then it is something to do with your sample/zone/keygroup/program/part/FX/multi settings! (there are pan controls for all of those - check them!)

If no, then it is most likely a hardware fault. Check your cables first, obviously...