More likely than not it's the loader putting too much pressure when it's spinning at speed, which in turn could be wearing the detents too much. Because the Halo based loaders don't have any active monitoring of the ball stack they can be prone to being a bit forceful, particularly at the end of a string of shots which is why they did the Magna to introduce a bit of slip. I'd try another borrowed loader, if that's fine when shooting strings then you've got the prob and can cock about with dem magnets.