ok im gonna put some lunsford turnbuckles in my XXX-T one of these days but i have never figured out how to get the turnbuckle holder (that little plasctic thing) off of the little metal ball?!?!

here a pic to show you whats i mean
i need to get that yellow thing off of the holder in order to take the whole turnbuckle out... ive pulled with all of my strengh but it wont pop off!!! WHAT GIVES... i hope my explanattion isnt too confusing... *sorry the pic quality is crap