Try to spin the inner spin tub by hand, it should spin CCW just fine but not CW. If it spins CW easily you are looking at replacing the transmission as the one-way bearing you mention is part of the trans, cannot be purchased separately AFAIK and cannot be replaced without special tools. Not a difficult job but you will want to replace the tub bearing, seal and trunnion lock bolts while you are in there. Throw in a new belt for good measure. I've got some more tips if you actually plan to do the job.