I'm new to R/C, but I spent a lot of time as a boat mechanic. When steel bolts get stuck in an aluminum block, the best way I've found to get them out was to treat them to a liberal dose of Liquid Wrench or similar, wait a while, then try to get the bolt to tighten just a little before loosening. This will work most of the time. You can try whacking with a hammer while the oil is seeping in, to help it coat as far down as possible. The dissimilar metals sometime react together like they are welded. Hope this helps. Jim