Ok to adjust balance to achieve center vocal image?

Hello paulgardner,

     An imbalance could come from numerous sources, it may be best to use a process of elimination to narrow down the root cause of the problem.  Here's some suggestions:

1. speaker cables- with the amp off, swap the left speaker cable with the right speaker cable. Turn the amp back on, set the balance control to the center position and try it out.
      If the center image pulls to the opposite side, it's your amp.  If it still pulls to the same side, suspect the speakers, the cables/wire or your room.  You can verify your speaker cables are fully functional with a continuity check using a multimeter yourself or just bring them to an electrical repair shop and have them verify they're good for you.

2. speakers- with the amp off, switch your left and right speakers and connect them with speaker cables you've verified as fully functional. Turn the amp back on, set the balance to center and try it out again.
     If the center image moves to the other side, it's your speakers. 

Best wishes,
    Tim

     Yes, thank you toothroyd.  A faulty interconnect cable could also be a possible root cause just as improper stylus tracking in the groove could be a root cause. The process of elimination should enable you to narrow down the possible root causes. 

Tim