I think you mean the "studs" in the cylinder casting. If you take the head off, you might be able to grab it with a pair of vice grips and turn it out. If it broke flush, it would have to be drilled and tapped out. Without seeing it, maybe you could take the cylinder right off, and take it to an automotive machine shop, to get repaired, to avoid buying a whole new part. good luck. ps if you try to use the vise grip method, use heat from a propane torch on the surrounding metal to make it easier.