Cambridge Audio 840C balance problem

I purchased an 840C used on ebay. When trying it the volume on the right speaker was 3 decibels louder than the left (according to the adjustment in my Rotel RSP-1068). When playing my current Rotel RCD-971 CD player the speakers have always been balanced just fine. Is there anything that could cause this within the 840C? It seems like an odd problem to have. The remote has a mode button for volume/balance control but this is for the complimentary 840A amp. That being said when the speakers were balanced by the adjustments in the processor it sounded better than the 971. I wouold like to get another 840C but want to make sure I am not doing something wrong.

System - Rotel RSP-1068, Rotel RB-1092, Rotel RCD-971, Paradigm 60,40,20,center v2