I've just had one of the carriage bearings start to seize up on my DeWalt radial arm saw. The bearings were very rough and lumpy feeling. The Nachi 81004 bearings are not available at a bearing house, and the OEM replacement price is ridiculous. The bearings have pressed on metal dust shields that are impossible to get off with destroying. With nothing to loose I tried to revive them. I removed the bearings and cleaned the dust & grease off. I put them ON EDGE in a small plastic yogurt container. I filled the container with SAE 30 engine oil to about 3/4 of the height of the bearing to allow air to escape and oil to enter the bearing cavity. I left them overnight. Next day I removed the bearings, wiped off excess oil and ran them back and forth on the bench. They came back like new - smooth with no roughness at all. I reinstalled and set up the bearings. My carriage hasn't felt this smooth in decades. I don't think the oil will last as long as the original grease, but it is an easy job to do this bearing revival. This is an inexpensive and quick way to revive your bearings if they have pressed on metal shields. Rubber shields & seals are easily removed. There is a good video if you search "bearing seal removal". Give it a try. I won't cost you anything but an hour or two of your time.