I just replaced the cylinder stop on my model 67. I fit the ball to the cylinder notches and then filed the stop to time it with the trigger.I measured the thickness of the ball and it was 0.007 inches thicker than the old ball.With the revolver back together timing is great ,double action fire is great and lockup is tighter than before.The problem is occasionally when I push the thumb piece and try to open the cylinder it is hard.Can the ball thickness be a little too thick? The binding does appear to be due to the tighter fit of the new stop as compared to the older one.