Researched typical causes for this problem online and replaced the part that seemed to be the most likely culprit: the clutch assembly. I purchased this part locally and installed it, but the problem persisted. Enlisted the assistance of a local repair technician who diagnosed the correct parts that needed to be replaced: basketdrive and washer drive block. Ordered these parts through AppliancePartsPros, and much to my amazement, received them the next day. Replaced these parts with the aid of one of the excellent instructional videos on the site, and now my washer is working again.