This is about my Heathkit GR-2000 but it isn't my only set in which this has been a problem area.
Most of the controls on the convergence board are unmarked, leading me to mess with this one which the manual says not to adjust. The form was cracked when I got the set and is now broken completely off. Unlike the service manual for the other set I'm ironing some convergence bugs out of none of the books tell me what to do if the adjustment gets thrown off. I re-wound the loose windings as best as I could and tacked the wires back onto the base.
Since I had no adjustment data it was best guess Mr. Sulu...
I finally decided to try to equalize the waveforms on both sides of the coil. Yellow and blue are no longer splitsville on the right side as before but I have no way of knowing if I did the right thing. Attached is a partial schematic of the blue convergence network including the blue pulse shaping circuit, I'm hoping someone can chime in on how to properly adjust these.