Here is the Al frame. I have cleaned things up a bit since then and it all appears true.
These are the disassembled rails and support extrusions. They all appear to be fine.
Here are the blocks and the ball bushings. The blocks were running very rough on the rails. It appears the heat has distorted ball bushings and bearings. They can be replaced once I figure out how to get them out of the guide blocks themselves.
A set of replacement bearings and I should be away. I think I have enough rail to make up all of my axes.