While installing my front wheel I striped one of the screws for the pinch cap with a 5mm hex socket. 3/16 is even smaller and the 7/32 is to big. is there a special driver for these srews.
I don't know the size but might suggest a high quality 6 point socket. It doesn't seem like a bolt with that small of a head should be that tight. I use one of those impact drivers you tap with a hammer and 6 point impact sockets for the bigger stuff. It probably would not be practical in this case but it has saved my bacon more than once over the years.