Buy some 3-in-one oil, the kind that specifically says for 1/4 hp motors or larger. Remove the bearing, after you have done so wipe the shaft with a clean lint-free cloth. Next, wipe the lower side of the bearing off with a paper towel. For the next step you'll need some Q-tips. Basically, what you're going to want to do is put a few drops of 3-in-one on the tip of the Q-tip and use it to clean out the bearing. Repeat this until the Q-tip comes out clean. After you're done with that, fill the bearing with oil and let it soak for awhile. Drain off the excess, put a drop of oil on the shaft for good measure and reassemble.
I hope that helps.