cylinder bolt/stud removal and installation

do you have a old oven? or a old pot you could boil the cyl in over a fire?
you need to get the cyl hot to get them out easily with out messin up the threads most of the time-
not suggested to use a home every day oven- because of the chemicals/ ect...

but if you can-- try a double nut on each studd--tighten them against each other and loosen the bottom one up towards the top-
good vice gripps work too- if your going with new ones
if you don't need to remove- just use a wire wheel/ and a dremal to clean each studd