The lathe stopped during turning, and the bearing is LOCKED tight.

How do I release it?
How do I inspect it for damage?
What do I do?

To free the bearing, first release the outer locking ring, then release the inner locking ring. Tap the end of the spindle with a rubber mallet, this will then loosen the bearing. 

To remove the bearing for inspection, take off the inner locking ring completely, the bearing will then slide straight out on the key way. Look for heavy ridges on the inside of the bearing or uneven wear. If you find the bearing has these characteristics it needs replacing.

When replacing the bearing first tighten the inner locking ring then tighten the outer locking ring. To test for correct setting put the belt on the middle speed, start the lathe as soon as you press the stop button the belt needs to turn 4 revolutions - The belt not the spindle.