I have had many zipper grips break off on my checked luggage. What causes this and does anybody have any tips on how to zip the bag to prevent the breaks? Zip all the way, leave the zipper on the corners, side, top, bottom or an area with a little slack? I normally pack my bags pretty full, if that makes a difference.

Perhaps related, I get areas where the zipper teeth fray, usually around the corners, and it's difficult if not impossible to pull the zipper around the fray.

Seems like a pretty trivial question, but I'm packing up now for a big trip and keep zipping and unzipping my broken luggage as I keep remembering things I forget to pack. Its so tedious.