I have several bolts which I need to remove and which don't want to budge. These are 1/2 inch or so, probably stainless steel, and are threaded through a finished (painted) plate and then into either another metal plate or through that second plate into a nut. They are also covered in bedding compound which is probably as old as the boat which is 30 years. I've soaked them in PB Blaster and WD40, banged on them with a hammer, all to no avail. I really do not want to heat them as that will discolor the painted plate through which they are fastened. I've looked at Sear's 'hammer drill' but that seems to just either drill or hammer but not both at the same time. Any suggestions? Thanks.