On an S&W, the hammer and trigger won't move unless the cylinder is fully closed and locked in place. That is normal. If it takes pressure to close the cylinder fully, then the crane might have been knocked out of alignment, and the others are correct; it is a job for the factory or a skilled pistol smith.
That said, my solution to that problem was to study and check everything very carefully, then whack the crane with a chunk of 2x4. But then I really did know what I was doing. (If this sounds awful, don't ever watch a body man adjust the hang of your car door!)
Jim