to tighten the bezel, you must first remove the movement
pop the crystal out
then remove the center bezel
remove the tachymeter ring.
under here you will see three screws that hold on the bezel (maybe two, i cant remember it's been awhile). unscrew these and remove the bezel holder ring. clean these parts and the case surface where the bezel rotates very good. apply light silicone grease on the holder and bezel. reassemble the bezel holder and tighten the screws a little at a time untill it turns with the correct feel.
reinstall the tachymeter ring, crystal, and inner bezel insert, replace the movement into the case and you have a perfect bezel.