[smokedetector]

My husband has a Honda Rebel and he's having problems with the chain derailing when he's riding, he thinks because the chain is old. He tried to replace it, but found the back gear "thing" (forgive my lack of knowledge her) was all beat up and had to use a pry bar to get it off. He has ordered new parts to replace the gear, including 4 of those interrupted screw things, but he is having a problem getting two of the original ones out. The threads are damaged, so he can't do the thing where you screw 2 nuts on and unscrew it that way (if you know what I'm talking about). How would you get them off? Liquid wrench? Would WD40 help? Are there special tools? He figures he can't be the first one to run into this problem, so any help would be appreciated.