I had a worn out cross-feed lead screw on a 1962 Colchester Triumph.
There's no problem getting lead screws material, just matching the end
with the bushing and pinion.

I bought a new length of lead screw and and a new bronze nut. The nut
had to be machined to fit, but they're supplied oversize for this.

I cut off the old section of thread and kept the section throught the
bushing and the pinion. Throught this I bored and reamed a hole on
center. I machined the end of the new lead screw section with a
matching diameter. The fit was reasonably tight, but I put a split pin
in just to make sure.

Bruce