Opening the back did not get me very far. It does provide access to the focus adjusters for the lenses, but I will wait until I can have an assistant to watch the image while I try to adjust the lenses.
I did get the lenses and mirror cleaned off. It does have an actual mirror and not a sheet of mylar. The picture looked better after that.
Removing the front speaker panel, reveals another access panel. This panel has the convergence board on it. I did not count the all, but there are a lot of pots on it for adjusting the CRTs.
There are three that are labeled red focus, green focus, and blue focus.
There is one bank the has columns for Red Vert, Blue Vert, Red Horiz, Blue Horiz.
The rows are for Tilt, Bow, Pin, Key, S Key, Size, and some other I can't think of right now.
There are a few more that are for some of the green settings.
Making sure that I noted the original position before I adjusted any settings, I was able to improve the image a lot. Mostly by adjusting the tilt, bow and in on the blue. red need a little adjusting as well.
I will try to take some pictures over the weekend.