Ed; I have the same old saw as you. If I remember right the ball turns with the lead screw. You are right it isn't much of a bearing but then you don't change it that often. One trick that I learned somewhere, is to take the lead screw out of the saw and put in a piece of 3/4" plywood inside the metal side. use a few sheet metal screws. Make sure you drill a hole where the lead screw goes throughit. The plywood stiffens up the whole side of the saw, and makes tilting more accurate.
Also when you have the lead screw out of the saw take tooth brush and clean it up good. Then take your tooth brush and put on a coat of Johnson's paste wax on the lead screw. I never did put the screw stops back on when I was done. the Screw stops never seem to work right. I find that I do better with a square.
Hope this hels some.
PS when you tighten the two screws that hold the ball in place, Don't overtighten them or it is real hard to turn the handle.

Steve