Pass Labs XP30 problem

I recently bought a Pass xp30 pre amp from someone. I hooked it all up and one chassis (left channel) seems to produce sound, but not the other (right channel).  I know the problem isn’t the amp and the xlr interconnect to the amp—if I switch the inputs to the amp I get sound from my right speakers. 
It was working fine for him just before I bought. I’ve checked the gain jumpers inside and they’re set to 10dB. 
Anyone who has an xp 30 have any ideas?  Thanks. 
Ag insider logo xs@2xssmaudio
Did you try it with RCA’s? Or swap left out to right in etc.
Never mind!  Forgot to check the input to the right channel of the pre amp. Incoming rca from CD player was bad!  How stupid of me. Aaaargh!  Thanks for the suggestions
Yeah, would be unusual for a channel to just die like that. 99% of the time it’s a cable issue of some sort! Congrats!