If you call the item by its correct name, a variator, you will have more success in your online searches.
There is a madmodder thread on disassembly and fettling, as well as one on Practical Machinist.
Two commercial sources, should you need them, are Allspeeds and Nottingham Electrical Transmissions.
As well as the factory manuals which Stuart will no doubt avail you of, download the Harrison 10AA manual from
http://neme-s.org/Shaper%20Books/Harrison%20Model%2010%20AA%20Lathe/Harrison%20Model%2010%20AA%20Lathe.pdf
as this has a section on variator maintenance.