Lol! I have a few boxes and bags of misc metric and sae hardware of the small variety kicking around... I have been in rc for a LONG time. After running some of the older cars, a hardware kit was just a necessary part of racing.
Have you taken the slipper apart to inspect it? Make sure you haven't got any wear damage going on? If it has been apart, take care to be sure all the parts have gone back in with propped order. The design of that slipper appears that if it's worn, unscrewing itself would be a likely result...