Using Kitchen's repair manual - available online- I took the machine apart and found the plastic worm gear was missing some teeth. The mixer is built like a tank and worked like a champ for 30 years so I decided to fix it. The worm gear is available separately but I decided to replace the whole bracket as a unit as it was not much more expensive and saved some work. The only hard part is removing all the old sticky thick grease which I felt I had to do since the ground up missing gear teeth were in there somewhere. It now works like a charm and hopefully will last another 30 years.