how to fix loose decorative nuts on bolts (light fixture)?

Purchased new ceiling fixtures with screw on decorative end caps. The end caps are not stripped, but they are too loose and wont securely tighten (ie spin freely)-almost like they are a 1/2 size "too big"

I Like the fixtures so prefer not to return them.
Need to be able to unscrew them for occasional cleaning so glueing them on is a bad idea.

Currently I tightened them onto the bolts by adding a few tiny strands of cut copper wire from an electrical cord-similar to the trick of adding wood strands to a screw hole-- and then they sort of screwed on and seem to be holding.

Does anyone have any other or better suggestions -I'm not sure if this will be secure enough long term? The 4 end caps secure a 2 pound glass bottom to the lamp...

 

Welcome to the forums! Since we don't know the model number or make of the fan, could you let us know that, and you may want to post a picture or two, since we can't see what you see. http://www.doityourself.com/forum/el...your-post.html