I took a vtx1800 into my shop last week, the tube around the rear spark plug was rusted away causing an oil leak from out of the cover. The threaded part is STUCK in the head. I had a special tool that you csn drive in and spin it out but its so tight i sheared off my tool then i had to dig the dang tool out. Now, i still have to get the remains of the tube out. Any ideas?