Charlie,
The large pump can be successfully rebuilt so that it will not leak. The shaft rubber o-ring is a key part of the sealing. I will need to look to see what size o-rings I've been using for this, but what is more important than the stock size is the "sizing" that you must do to the o-ring once it is fitted to the shaft. As I recall, this step was not included in the Tech Manual and I have never been able to fit a stock o-ring, right out of the box and have it successfully seal the shaft. Essentially, what I do is to install a small o-ring--I'll find the size out for you later--onto the shaft. It needs to fit very tightly so that it does not slip during the "sizing" process which follows. After fitting the o-ring, chuck the armature assembly into a drill press with the seal side down. Try fitting the bellows seal onto the shaft with the grooves facing downwards w/o forcing it. It should not at this point slip past the o-ring. Remove the bellows and turn on the drill press while holding some fine sandpaper against the rubber o-ring to sand it down and reduce its outside diameter so that the bottom of the bellows just slips past it. This is a trail and error process and you may have to repeat it several times until the bellows slips past it. The key is not to force the bellows on, yet when it does go past the o-ring you want it to lodge tight against the top (grooved) portion of the bellows--the inside the holes on both ends of the bellows are of slightly different diamters- this is how you ensure a fuel tight seal in this area.
George Des
