Ok, I took my heads off to put new valve springs and valves, and so on. Well, I compressed the spring with a valve spring compressor, but this is where my problem begins. I thought that when you compressed the spring the valve should be able to be pushed up to take the keepers out so that the spring can be removed, but the valve won't move. I tapped on the sides of the rotator on the exhaust valve, but I still couldn't get any of them off. what am I doing wrong, and what do I need to do to get them off? thanks