Rebuilding a Hawley Mark II X063X mouse?

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?