Worm drive/transfer gear stripped under stress of dough kneeding (25 year old machine)
Watch the video, it's excellent. Carefully remove the uncorrupted gear grease under the cover and save--there should be more than enough, and replacement grease is expensive. Don't be surprised if punching the retaining pin from the worm gear takes some persuasion--you'll need a small punch and perhaps someone to stabilize the tower while you work. This is a very satisfactory repair project, and it's great to have "old faithful" back for such a small price.