An easy fix normally: press firmly and roll the ball in the direction in which it does not want to move. That will normally clear the trash or lint that is holding it.
If more serious... you can easily replace one, try HorizonWirelessOnline.com - Horizon Wireless, The World’s Cellular Repair Center ß
. They are simple to replace.
Nevertheless, a warranty is a warranty. At what point (how long) do you want them to extend your warranty, after expiration? I do understand though, customer retention should stand for something.
Do you carry your 8830 in your pocket?