:doh: bleh! Sounds like the bolt corroded itself into the hole. We used to 5th gear job as a last result when I first pulled mine, and luckily it worked. Have you soaked the bolt in anything like Wd40 or AeroKreoil? I'd suggest the latter if you can find it. It displaces water and lubricates down to a tiny tiny tiny level. We use it on the helos all the time for our stuck bolts. The only other suggestion I have is to rent a torque multiplier. It basically snaps onto your ratchet and multipies whatever torque you put on it by 2 or 3 or 5 or 10 or whatever the setting is. They use them a lot in aviation for prop bolts and the jesus bolts that attach the rotor to helo. The only risk you run with one of those is shearing the head of the bolt off.
When you do get the bolt out, be sure to chase the threads on it, and in the hole... just to clean whatever corrosion you have, and help prevent new corrosion from forming. Good luck. :thumbup: