Since oiling and tapping of the shaft has helped I would also ask LMC if instead of the normal machine oil if something like a good penetrating fluid or Synthetic transmission fluid or even diesel fuel would be another alternative combined with oiling. I don't use regular sewing machine oil in any of my own sewing machines. I find that a mixture of Synthetic transmission fluid and Synthetic oil works much better but I am willing to take the risks associated of going outside normal sewing machine