Try here for a new crystal http://www.invictawatch.com/support_files/service_center/ServiceCenter.htm
If you cant get the correct one then just go by size. As for getting the old crystals out, sometimes it helps to warm the bezel up, I am not talking about soldering heat hot, just very warm, it expands the metal and makes it just a touch easier to pop out the old crystal.
Nice watch 
