I assisted in a quick-and-dirty today on a PG 6100 (I think, might have been a 9100.) Several of the alignment and convergence controls do almost nothing... nothing like the range I'm accustomed to in my experience owning a 9100 and 9200.

The F board looks to have been repaired (traces from deflection connector pins to adjacent pad had to be supplemented/replaced with some bus wire apparently) and this set was allegedly sold by Curt to the previous owner.

Is there anything obvious that would make the Bow, Keystone, Skew, and several other controls virtually meaningless?

STK392040 on the c-drive might explain it.