Broke a few bolts off in frame...need help.

Thanks guys. I may need to re-tap. Im going to tackle it this weekend, I have some bolt extractors but I have been reading that left-handed drill bits may be the way to go. I plan to heat the bolt, center punch it then either use the extractor or the drill bit, taking care not to get too close to the nut threads.

Im wondering... I looked in the fiche and it sorta shows a cross-section of the area. I assume its hollow inside with a nut welded on to a plate, or right on to the frame part. I also assume over the years the part of the bolt sticking freely up into the frame has rusted. I wonder if it would be easier to spin the bolt INTO the frame, which sounds easier than pulling it out. The bolt would be rolling around in the frame but I could fill that area in with some sort of rustproofing or something to prevent it from rolling around?