First, it should be hard to turn unless you press down and turn.
If it is stiff when you press down and turn, take the bezel off and look at the thin flat washer. If it is bent, make it as flat as possible.
If this doesn't help, inspect all pieces for burrs or epoxy.
Sometimes the inside of the insert itself is very tight on the crystal....in that case, sand the inner diameter of the insert or replace it.
Other than these, I can't help....