The stem was a royal pain, as it was already beaten with a s***** stick from underneath I gathered the PO had already tried to get it out, after ages with plusgas I got it to rotate but that was all, it proved to be the only way to get it out it was brute force..... I know I know yeah yeah yeah but it's just a syncros stem.
Pulling up a chair - I love stuck seatpost stories..... Hope you are faster than me at this kind of thing or I'm going to need a lot of pop corn - my last stuck post took me about three months to remove, though most of that time was soaking it in various fluids