I have a oil furnace with a hot water coil. The furnace started leaking water. I removed the cover and found that the plate that covers coil chamber was rusted and leaking. I had to cut off the heads of ten bolts holding the plate on. How can I remove the cut off bolts from the housing? Should I try to use a easyout or try to drill them out and retap, or is there some other way to get the cutoff bolts out so I can put a new plate on.