The battery cover on my Pearl has been driving me crazy. It was loose and shifted every time I tried to type. I know there are replacement doors out there but here's a low-tech idea that completely solved the problem:
Cut your business card in half and insert it under the door. Just lay it on top of the battery and put the door back on. Problem solved.
a couple pieces of electrical tape on top of each other works 10 times better than the business card....just don't put like 4 strips because the cover might not come off to much because of to much friction.
I think I am using 2 on the battery and a small strip just south of the camera area...and havent had a problem sense.