Mo, the three part gear acting as one piece, right above the 2006, serves three purposes, two gear ratios and the square/flat gear which meshes with the "ladder", visible also. Both chucks turn at the same time.

That machine has an original depth stop still in place, I had to make one.

Gabel, you can see the round pipe at the left of the picture, at the base of the machine, there are three of these. I had a dyslexic moment when I said shims. You may have to take material off these to bring the sides closer together.

Do you know if the rails are worn? Or the head? The rails don't see much wear down at the bottom, measure the difference top and bottom and compare. Is it side to side slop or front to back? Rust would contribute to the removal of metal, too. Is it rusty?

Would the Delrin go in the groves in the head or on the rails?

I wonder just how much wear would show on these machines? I can see the shafts wearing and they do. I have oil ports drilled in mine, I use various oils to lube the working parts, whatever is handy. I don't however lube the rails.

Another item deserving of attention is the two latches, one holds the head up and the other engages the ladder. I have adjusted the slotted screw just so, so that the mechanism swings freely and does not catch of the side, I had to tweak/bent one to make it work proper. I would not use lock tight to hold the screw in place, even the mild grade, but silicone would help hold the screw from working out.

Tim