Sorry to bump an old thread, but...
To all the people with stuck joints, please follow the advice in this thread. I had a downstem that got stuck due to a combo of waterlock and taking a pretty hard direct impact to the top of the downstem, seemingly cementing it in there, yesterday. Well, after tapping it on a bookshelf and trying to pry it out with my fingers over and over for more than a day straight, I decided to try to pry it out with a flathead wrapped in thick paper towel. (dumb idea, I know)
FUCK! Snapped a giant ass chunk out of my beloved Alex K dowstem that lasted for over 8 years.
Then decided to search the forum, but only after I broke the stem of course. (d'oh)
I used a Blazer torch to heat around the outside of the joint to evap the water in the joint. Then after it cooled a little gave it several good taps around the outer edges with a wood spoon. Repeated a few times, then voila, the stem came out!
I'm so pissed at myself for not searching first, and trying to use brute force instead.
Luckily, the downstem was quality US glass, so it didn't shatter into pieces, just one big chunk broke off one side. I'll probably just gorilla glue it back together.
Learn from my mistake... A torch, a wood spoon, and patience will work wonders.