If you are really stuck and have exhausted all other options and have absolutely no other alternative, short of removing the slave cylinder to work on it, heat will loosen it but a propane torch won't cut it. You will need an acetylene torch with a pencil tip. With that set up you will be able to get the bleeder very hot very fast without heating up the surrounding slave cylinder very much. This of course assumes that there is sufficient room to get in there with a torch safely- I don't know if that is the case or not. I also do not know if there is enough room between where the bleeder is and where the seal is located to prevent seal damage. Some of the guys here who have changed the slave cylinder (Pete) might be able to offer an opinion on that. It will usually come out quite easily once heated. You will want to replace the bleeder screw of course and flush all the fluid out. I have had to do this on brake calipers before and have never damaged any calipers or seals doing this but I have experience with acetylene torches and seized fasteners. You might want to loosen the fluid line before as well just as a pressure relief valve in case you heat to much and overheat the fluid if you are uncertain of the process. Do not remove it however- you want fluid in there to absorb the heat to protect the seal. If you decide to attempt this and have never used an acetylene torch before you might want to have someone who has experience with them to do it for you- 6, 000 deg. F can do a lot of damage very quickly. Again. this is a last resort of course only to try avoiding removing the slave cylinder. I am assuming that you have tried all of the usual methods such as the penetrating fluids, tapping it with a hammer, rocking it back and forth if there is any movement at all, etc., etc.. Another trick that I have heard of is quick freezing it with one of those cans of quick-freeze which I assume is nitrogen. I have never tried this so I can't offer an opinion on its efficacy.