What is the best thing to get the visi glass out from the rock hard gasket I have soaked them in oil before but doesn't seem to work nothing seems to penatrate .Any tips would be great. Thank you Jason

Small drill bit rotated between index finger & thumb.
Wear a dust mask & dispose of properly, keep pets away from dust.
Below link tells why it was used;
Litharge Glycerin

I don't know if it always works, but I used Muriatic Acid on one and it really softened the cement material. Be sure you are well ventilated.

Do not use Muriatic Acid in proximity of Galvanized castings or Alum. Will dissolve Galv. & Alum. will cause boiling w/ vapor fumes. Best to use outside away from any bare metal.

I used it on a cast iron body. Thanks for the advice! I should have been more thorough in my answer. It is safe on brass also isn't it?

Will remove some/most of oxidation.
Use Household Baking Soda mixed w/ water to Neutralize acid & a clean water bath, blow dry to prevent oxidation/rusting.