Just a thought, once upon a time I thought the problem was in the upper arm as the hand wheel had a sticky spot. Turns out it was in the bottom. So be sure to keep oiling the bottom as well. I've used kerosene to clean out old oil, but followed up with sewing machine oil. As you are oiling keep turning the hand wheel to distribute the oil.
You are so lucky for having a manual, even if it is not as straight forward as one would like.
Janey - Neat people never make the exciting discoveries I do.