I bought a used manometer that was stuck, frozen, completely immobile. One glass blower recommended putting it in the freezer. I tried it, it didn't work. I also tried heating in an alcohol flame and that didn't work. I finally brought it to a glass blower who got it unstuck in one minute flat. He heated it in a flame and gave it a knock with a wooden stick. He said the trick was to heat the outer joint quickly so it would expand, while the inner joint was still cool, then give a quick tap with a stick. He didn't even charge me to do it! I would try cola, the freezer and heating... and then bring it to a professional before you break it and need to have it repaired.