What material to use for geared shaft

[Pete O]

As Darren requested, some photos of what is there, and I'll see if I can upload a page from the PDF manual with the exploded view;

In this photo there should be a shaft with a universal joint at either end, going from the middle left to the top left of the gearbox in the middle of the photo:
   

This is what I found when I opened up the gearbox:
   
The circlip is there too if you look closely.

The shaft is supposed to enter the gearbox through the bush at the top left of the above photo, which has a 3/4" bore, then it drives the gear, which has a 7/8" bore, and is supposed to be in this position:

   

then the shaft exits the gearbox through a bush that is supposed to be in this hole (this hole in the casting is 1.5" diameter);
   

and goes across to this other gearbox, which appears to be where the trouble began:
   
   

The second gearbox contains the worm arrangement that sends the drive up to the gear train in the top part of the knee that drives the X axis leadscrew. This gearbox is mounted under the table thus has to move in & out in the y axis, with the shaft sliding through it. I'm deducing that the oil level in this box was neglected (it's sort of hidden under the table) resulting in the worm gear inside it seizing on the shaft, which would have prevented any movement of the table in the Y-axis, so someone has simply cut the shaft either side of where it is seized and removed the remainder. The casing of the worm gearbox is also cracked, presumably from someone trying to force movement in the Y axis after the shaft seized, so i will have to either weld it or make a new one (who do I know who has an iron casting furnace...)


I think I'll have to scan a page of the manual to get the exploded view, will do that later