GEC52,
It is possible, but is a job that requires some proficiency to be done. Not all that hard, but can be done. You'll have to pull the oil pa(i)n, loose all the main caps bolts in a way that the first and second front main cap does not fall, remove the other (3 & 4) main caps, the crank will go down a li'l, then You'll have to remove the upper rope using a lot of patience, a thick wire may help a lot, try to clean the channel completely, You may use a small plastic bottle with querosene/gasoline/thinner to make sure it's clean, spraying the cleaner in there. Or any other stuff like carb cleaner. After it's all done, make it dry, slip a new neoprene seal, put new bearings on it, remove the ones in the engine, they should be worned out, and assemble it all carefully. remember to torque carefully the main caps, should be a good idea to replace the rod bearings also and prepare yurself to put the oil pa(i)n gasket carefully, so it does not leak and You'll be fooled thinking all this job took you into another oil puddle!
Hope it has helped.
Truckernix
It will go down a decent amount when You unbolt the main caps. There is a fair amount of play in the input shaft bearing, and remember the pilot is not all that tight into the clutch disc and into the bearing. In such a situation 1 or 2 extra milimiters - .040" to .080" is a lot of space to play. In fact it will go down much more.
I'd go the neoprene route also, would put a dab of glue between it and the block, and would also change the main bearings. Of course Dude that's what I'd do, and obviuosly I can be wrong! Just my 0.02.
