with helicoiling you re-tap an m5.25 thread into your frame, then screw what is essentially a steel spring in; this replaces the m4 thread that used to be there. This will NOT come out if its heated if fitted properly. The cut and clean thing is properly just a tap used for cleaning threads, if the threads have gone, then the materials probably gone from inside the mount, hence leaving not much to tap into A helicoils' most likely your best option in my opinion, will cost you around a fiver per thread at most garages.