Hi, Richard -
I, too, had a maxillectomy on the upper right side, and wear an obturator. I will soon be getting my permanent obturator made -- have been wearing a temporary one for about a year now -- and would be happy to answer any questions you have, if I am able. Stability can be a problem (as "Wheels" said above) if you don't have sufficient teeth for anchoring. If you do have your upper left teeth still, you should be able to have your prosthodontist adjust the obuturator for maximum stability. Mine wiggles a tiny bit (I can make it move with my tongue), but not enough to be bothersome. Don't be shy about returning to your prosthodontist as many times as you need to in order to get this thing stable!
Feel free to ask any more questions that come up. There aren't too many of us with obturators...