I have a 1989 88 SPL Im trying to put a new water pump kit on it and I cant get the impeller off. I know there is a small plastic key way but short of cutting all of the rubber off the impeller and cutting the sleeve its molded too. I cant seem to get it to slide off the shaft. I have sprayed it with PB blaster thinking it was corroded but have had no luck. Any help is greatly appreciated.