Drill the center of the remaining stud, 4mm (5/32) should be ok then using an Eazi-out slowly but firmly turn the eazi-out ANTI clockwise at the same time gently tapping the eazi-out with a hammer.... DONT belt it, just enough to stop it slipping,whilst still turning, and the stud should come free.. Might be wise to soak with WD40 first and let it soak... Hope this helps....Wilmot (Liege-Belgium)