I have been having some problems with the inner axle on the left \ Driver's side coming out.  The axle looks OK to me but that doesn't mean much.  It has the circlip on the end and when installing it goes almost all the way and then requires a little tap to install completely.  I added a 15" limit strap and will next look at full droop and stuff to see if the axle shaft pops out. 

Any thoughts as to why this would happen?

Need a new inner as too warn out or something like that?

Could the inner axle be popping out slowly from a worn out but not failing C-Clip? 

Is there a specific C-Clip or would the below work? Do I need the Optional O-Ring to go under the C-Clip?
https://gorilla-axle.com/shop/Replacement-C-Clips-for-Inner-CV-Joint-p168849681