At the prices of new cylinders, replacing the O-rings are worth a try. Yep, those bolts were not fun but I finally got mine out.

hokie1984 posted this thread back in 2010 and it helped me decide to fix mine: Convertible Top Hydraulic Ram Sucess

I then ran into that bolt removal issue and hokie1984 helped again in this thread: Convertible Top Cylinder Removal

It's been years now and mine has worked without leaks since.