[racingdwarf]

If you have any bite left in the hex part of the grub screw you could try some heat, it will expand the metal around the screw a little and also break down thredlock etc. For Rc a heat gun is just the job as they get bloody hot, heat the shaft,yes the screw will get hot but the shaft will get hotter than the screw in it.

I agree with torx as if you can hammer one in then use heat….heat works wonders on seized bolts…drive shaft should be ideal as it's all metal