I'm sorry. I meant to post this a while ago but kept forgetting. Now I don't know how many people this can help but here it is.

Use little bits of poster tack under the battery cover and/or battery to hold it all in place. Yes, I mean the soft putty that was traditionally blue but now comes in many colors (I'm using yellow right now).

The idea had come to me after reshimming my battery again. I use poster tack to protect parts of circuit boards while heating, soldering, etc. It's minimally sticky, pliable, non-conductive and amazingly heat resistant. So I decided to try it on my Pre+. I has worked very well. So well that I forgot about it until yesterday when I needed to pull my battery because something caused my Pre+ to lock up. It took extra force to get the cover off and that's when I remembered what I had done.

I hope this helps someone.