This thing is probably pretty corroded up so I would start by taking the entire handle bar off with cable and then setting it grip end down in a container of mild lubricant like WD-40. That is, if you are trying not to do any more damage. If you do a minor balancing act you can place it in a slender glass or jar and not need to use a gallon of the stuff. The rubber was assembled with adhesive and can be difficult to remove without damage. Once the rubber is removed, you can pretty much see how to proceed with the grip pipe itself.
The book shows two styles of "friction units" and is contingent on serial number. Either #1000004 thru #1299999 or 1300001 and subsequent. The early unit installs prior to putting the rubber on and the latter unit goes on after the rubber is on the pipe. Obviously, the later style needs to be removed prior to removing the rubber grip and may need some strategically placed rust penetrant to loosen the friction piece. Be careful here as I do not know how well the rubber will tolerate a powerful solvent like that stuff.
You can remove the grip pipe cover (the part installed ahead of the rubber grip) by aligning the word shift with the red dot on the handlebar. That is, if all that is still readable. When properly aligned, it pulls off and pushes on and should expose the "cable hinge" when off.
Then it is simply a matter of soaking all the metal parts in PB BLASTER rust buster (or equivalent)...( what am I saying??...PB BLASTER has no equivalent!...I digress...) and getting things all loosey goosey again. This takes patience since the corrosion can be unpredictable and the rust penetrant takes time to eat away at the stuff. Soaking the parts and placing them in direct sunshine helps as well as adding some heat from a heat gun or hair dryer.
If my scanner still worked, I'd send you a page but alas, it is kaput!
Good luck.
