I have always used a method similar to cuyler1's. The only real difference is that I use Marvel Mystery Oil, pour it in liberally through the spark plug hole, then replace the plug and let it sit for at least 24 hours before trying to turn the crank....gently, at first, using a back-and-forth motion. Once you feel the rings break loose, you should be able to feel whether it's somehow still bound up, but I've never had this stuff fail me completely! Good luck.