I adjusted and squared everything. When I flip my pieces over and put them
back together they fit perfectly. Except...

The table is flat, but when I move the arm to 45 degrees, both right and
left, the blade is a sixteenth close to the blade then when it is at 90
degrees. This doesn't make any sense to me; it is like the arm droops a
sixteenth when I turn it.

Any advice on what this is, or how to fix it. Or, does it even matter?
Unless I am cutting a diagonal dado, it probably will never make a
difference, and I have never cut a diagonal dado. Any other times it would
affect the results?

Other than that, everything seems well in hand; I can't wait to see if it
stays in adjustment. The guy I bought it from says he got rid of the riving
knife and hold down because they are just a safety things and got in the
way. Well, I don't expect to be ripping on it, so it isn't much of a loss;
but they would be nice to have anyhow. Oh well.

No, there is one more question...
A while back people recommended "Fine Tuning Your Radial Arm Saw". What is
in there worth $15 that is not in the instructions?