These washers have been around long enough that we’re starting to see drum bearing and seal failures. Maytag has come out with a reasonably-priced bearing and seal replacement kit.
While you’ve got it torn down, might as well replace the belt.
Intimidated by this job? There, there, my leetle grasshopper, not to worry– the Maytag Neptune washer service manual is excellent and will hold your hand throughout this entire ordeal. Come git you one.