I converted several vintage singers to hand cranks, the last a late 40's 66 with drop in bobbin. My understanding is if the original has a spoked wheel it can convert, I got the cranks and parts off ebay over several years, made in China. Sometimes original parts come up but usually more expensive.
Hand cranks are pretty quiet on the whole, perhaps the one you were looking at needed oiling or needle adjustment?
Best wishes, they are much fun to use!
lots more experts here, they will correct my info if wrong
