Hi Paul
The slight wobble can be helped by running your VGA card with negative sync. Port 3 is worse for it, port4/5 should better etc.
The convergence drifting can be caused by a couple of other things excluding an actual fault with the convergence board.
A stable room temperature a must, as the big CRT lenses need time to warm through. Anything up to 3 hours from a very cold room!. So try to keep the room at the same temp.
The next tip is to set aside a convergence day.
Give the projector a minimum of three hours to warm through, showing a running program/film.
Then do a nutter convergence on each memory block, including a electronic focus if your machine allows it.
I also did a lense focus as well since they were at full temp etc.
I too used to converge on a daily basis, but since i did the above a have not needed to touch it at all in over two months.
The reward is a faster optimum film start time and a superbly focused and converged "highly" detailed image.
Above pic from Barcodata 808s/Quadscan Elite/Pioneer737