Thanks guys. I think I will try the lock washer idea.

This is another example of the auto industry using plastic in an area where they should have just used a metal part.

I'm sure all of us on this site could probably come up with 1000's of examples wheres auto manufacturers used plastic in an area where a metal part was better suited for longevity (i.e. clip, faster, screw, etc.). This is a pet peeve of mine especially with newer cars.