I had the loose-USB syndrome and rainbow LCD issue with my last TP2. The rainbow LCD issue is caused by too much pressure being applied to the LCD (e.g: pushing too hard on the screen), from what I can tell. I didn't realize this until after swapping mine out and reading up on the issue online.
The loose-USB issue appears to be an issue with using standard miniUSB cables in the proprietary USB port. It fits, it works but it is a little loose, and the issue isn't present with my OEM TP2 cable, on either of the TP2's I've had.
I use an iGo charger in my car for my TP2. The miniUSB tip works, but if wiggled a bit the phone will stop charging. Same with my old XV6800 USB cable and my laptop.
These are my observations, not facts. Check for yourself if you'd like, hopefully I'm correct and the issues are user-related
-mak