I have had some trouble in the past with Comp Cams locs. My 'decision'
was that some of the locs were missing the heat treat process. I had some that would wear the locating tange away and allow the valve stem to pass through. I saw it on about 3 motors in a year's time. Not ALL the locs did this, just a couple/three at each time. Also, both locs on the same valve did not fail, just one wore severely. Even this wearing of the tange did not wear the groove in the valve as your pic shows. All of these were caught at valve adjustment time, except one....my personal motor!! I found it after a valve pulled through at around 6300 RPM as I shifted in to high gear. These were all 10* locs/retainers from Comp. All square/single groove.