Front Axle Grub Screws
I had the issue with the lower front axle grub screws not holding in the chassis; the grub screws would just spin. I took several strands of copper guide braid (maybe 6 or 7 strands), twisted it together and put it in the grub screw hole, with the end of it sticking out, and screwed in the grub screw. This seemed to make it hold. It stayed firm through the race last week.
Russell