Also, you might remove the extractor and thoroughly clean the hole for the extractor stem. Wouldn't hurt to polish it a little with some very fine emery cloth wrapped, maybe glued, on a very small rod, or just rolled into a sufficiently small size to be inserted into the hole and worked in and out. Then, l'd polish the extractor stem with the same emery, and oil before replacing. The "notches" you mentioned are also to help begin the forward movement of the extractor as it is acted upon by contact with the nose of the firing pins. Any polishing and lubing will help ease that movement.
Good luck!
