you want the button end play to be less then 010 to all most 0 .i like the button to fit in the gear tigth .but if your running a lock plate it would be ok long as its not realy bad .i just use one of the BBC Edeldrock /china die cast covers .to say that it could be better is a under statement. i used a roller type button and set it at .005 i like to keep the end play under .010 on the roller buttons to get that cover to fit and machine the right end play i had over 3 hours in to a job that only takes one hour most of the time