Tool rest locking screw repair questions

The inevitable had inevitabled after just months of use. Not covered in warranty and like fuck am I paying these dicks after the way they spoke to me, SO! Do I re thread the cast part and move up a screw size or is a stainless insert the way to go?

Please turning family help me get my girl up and running this week, I have an event coming up and I really can't get a new banjo in time!!!!