I am cleaning up the two drive shafts now, have removed the four universal joints and got most of the 50 year old dirt off. However, the spline will not slide out of the sleeve. I can see dirt caked under the sleeve cap, so I would like to separate both shafts, but neither one will come apart. They do slide about 3/4 of an inch, but that's all. Is there a secret to getting them apart, or do I just need more oomph?