i can't remember what i read, but it mentioned something about how the plastic teeth that go onto the servo will get shredded or damaged somehow. can someone clarify this for me? i see on towerhobbies that they sell ofna inserts. why would they be selling so many of these?

http://www2.towerhobbies.com/cgi-bin...?&I=LXFNF2&P=7