ARC 75 SE Bias Issues

Hi - I’ve been a happy ARC 75SE owner for over 5-years. I just moved to a new house and in the process my beloved 75SE stop working, here is what is happening: when adjusting the bias for the tubes, tuve #3 bias adjustment will not respond, the gauge is al the way to the left and won’t move. Is this a tuve issue or something else? Any other ARC owners had have the same issue? Thanks!