Screw Problems

[dirtbat]

Any advice for the 2 motor mounting screws in the bottom rear end of the car under the guard. These nasty little suckers refuse to say seated. I have tried the usual cyano or epoxy re-threading, you name it....they won't stay in. This is a pretty stressed part so a proper fix is in order. I am considering 10-12mm M3 self tapping screws.

Has anyone dealt with this part before?