And while you are in there why not do the mod described below. These instructions were sent to Carl Hungness earlier today.
The modification is conceptually very simple and once it is done you will see why it works. All the work is done at the inside end of the C3, that is the opposite end to the shoes. The gearbox main shaft is 1” diameter and the outer diameter of the C3 is 1.25”. That means that the wall thickness of the C3 tube is 0.125, one eighth of an inch. The internal diameter of the ‘o ring has to be one inch to go over the shaft. If its section thickness was one eighth of an inch then there would be no shaft left so one needs an ‘o’ ring with a thickness of about one sixteenth of an inch, about 60 thou. I would get the ‘o’ ring first before your machinist chum starts to cut metal. Suppose that you do use a 60 thou section then he needs to cut the inside of the tube with an outer diameter of one and an eighth inch, that is the outer diameter of the ‘o’ ring, to a depth of about 45 thou. This will give a nip of 15 thou on the ‘o’ ring which is enough to make it act as a seal. In fact even 10 thou would do it and it is absolutely non critical. The reason to get the ‘o’ ring first is so that these dimensions can be changed if the ‘o’ ring has a different thickness to what I have used above. All that matters is that there is some of the outer diameter of the C3 shaft left and that the ‘o’ ring is nipped up to act as a seal.
Once this is done, oil just cannot get onto the splines and down into the clutch. In fact I even put a smear of grease on the splines and ‘o’ ring to ensure that it all comes apart if ever I need to work on it.
Best of luck with it
Norman