mr p are you any good with a welder ? cliff may take them out a different way . heres how i get them out . i find a small washer steel of course not galvanized that just fits over the screw . take your mig welder and spot the washer to the screw , let it cool a second and weld a little more , then take a small nut and tack it to the washer , while it if still hot apply canning wax to the surface by the washer , the heat will pull the wax in and lubricate the threads .if someone has bottomed them out ,the nut should still give you enough bite to get them out. fwiw