I have a Blackberry Pearl 8100. Its a nice handset but the trackball is the only worry. At times ball just moves one side and leaves the other side..
Let me know if any solution is possible...
I am not exactly sure your issue from your wording... but if you need any new parts, follow the advice given above ^^
That site seems to be the go-to-guy around here... and I have heard it is really reliable! I am actually looking to get a new trackball, LCD lense and possibly a new keypad from there!