Are you just getting the stem out, or did you unscrew the screw to much and need to reset the keyless works?
If you only getting the stem out, just unscrew the nearest screw to the stem. but do it slow and not mutch. put some presure out on the stem,
when the stem comes loose just stop unscrewing and you set to get the stem back into place. This is my logic, never did try this out on such a movement.