I been struggling to drill through my HS50 throttle arm to create a hole for the throttle cable. I’ve tried an Irwin bit for harden steel, but it didn’t work. I’ve had other engines that were drilled out on the arm before, but it wasn’t done by me. Any suggestions on a bit that would work? I don’t have a throttle assembly that is set up for a cable, otherwise I’d use it. I’m trying to modify this one to work. Any assistance is appreciated.