I've had wheels wear out and pop off and bearings get stuck on two longboard trucks in the past month now. I've gotten the bearings off and thus spared myself $100 expense,
How to remove and clean Arbor Rally Longboard bearings - iFixit Repair Guide
The Easiest Way to Get the Bearings out of Skateboard Wheels
All About Skateboard & Longboard Bearings - Much Awesome