Is it just the cylinder not releasing or the entire clutch? I'd separate those items first. If it is just the cylinder you sound like you are on the right track. If it is the clutch itself check the clutch basket and hub for any grooving, shallow grooves can be removed with a file while deep grooves require replacement. Best advice I can give is spend the cash on a factory manual, in my experience the Clymer manuals are oversimplified for use by the lower IQ portion of the population. Whereas the factory manuals I have used are much more indepth and helpful.