If the gap in the split locks is completely closed up the locks and/or the groove in the valve stem is worn out. I install all new split locks on every valve job- - - -it's cheap insurance. There should be a slight gap between the locks when they're in place and the retainer is pushed up snug against the taper.

It's easy to pinch a piece of the O ring between the keeper and the retainer, so if there's any doubt, re-compress the spring and check the O ring.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!