I've been thinking about replacing the scratchy crystal on my Mark 4.5 Speedy but an experienced repairman told me it was very difficult on this watch. Has anyone had this done or know of any problems doing so? Are the aftermarket non-Omega crystals worthwhile? Thank you.

 

The chrystal gasket should be replaced as well. The black dial ring is first fitted inside hard plastic gasket and flat rubber ring into groove of tge ring.The chrystal is then pressed into plastic gasket and finally the whole package into case. A very tiny amount of silicone will help in the final process. To replace the chrystal with old gasket will not work well.

Good luck!