Rebuilding a Hawley Mark II X063X mouse?

[Tothwolf]

Over the weekend while moving another project out of long term storage, I 
also unpacked the Hawley Mark II mouse for my SGI IRIS 1400 since I wanted 
to see what it might take to repair its cord.

When I originally acquired the machine, the outer insulation of the 
mouse's cord was just beginning to crumble at the ends, but 10+ years 
later, it has now become extremely brittle and is completely flaking off 
the cable. The cable they used for the mouse is very small diameter [my 
mouse has the same cord as this one: 
http://www.oldmouse.com/mouse/hawley/X063Xvanilla.shtml] and I don't think 
I would be able to find a multiconductor cable that small to replace it. 
The individual conductors are still tightly twisted together along with a 
fiber wrapping of some sort. Since the inner conductors appear to still be 
intact, I'm considering using heatshrink tubing to replace the outer 
insulation, but I'm not sure if this would be the best approach or not.

In addition, the main ball doesn't turn very well and the rollers/contacts 
inside the mouse also don't move. I've not yet disassembled it any further 
than just lifting off the outer cover since I'm not sure of how involved 
of a project this thing is going to become. [I was initially hoping it 
would be a minor project to repair the cord but it's starting to look like 
repairing this mouse may be pretty involved.]

Has anyone else rebuilt one of these mice, and if so are there any gotchas 
I need to be watching out for?