here is two good tricks. when drilling i use a carbide ball mill 3/16 or bigger much better than a drill and will drill alot of tuff stuff but not cheap .i use the tooth pick type ezout and go as big as you can on the hole to use the biggest ezout out so it will not brake . and you can .heat it up and use and toilet bow seal the yellow wax type on the part you want out this works the best and try again