I have to admit, I cringed a little with the hammer use but if it's working, that's great.
I don't think you'll ever get an elna supermatic to quiet down to 201 levels. 201s are amazing in their sound levels. I have a HC 201 I got around Christmas last year. After a good cleaning (and some body restoration) the only thing you hear when you crank it is the HC, not the machine. It obviously changes with thread and fabric on it, but not much. (At the time, the shellac was still too wet/fragile/new for me to run fabric on it.)
I don't remember what that motor was like. I'm sure it's got brushes though based on the carbon I found inside - so those should be check and the rest of that maintenance. I don't think it's a greased motor though. There may be a few bushings that would enjoy a single drop of oil though.
I think the pulleys warm up just like the tires on a race car, then they have great traction. The machine that ate that pulley didn't have an elnagraph. It was the mystery machine with the swing needle and no zig zag control.
The aluminum pulley thing looked like the best way to me too. I'm glad it worked for you and that someone made one for you.
I've never had trouble with the speed of the Elnas, it's just that I don't like the pulleys or that bobbin case (did you follow that YouTube video with all the stills? It's unreal what you can find in there! That will contribute to noise too - not all lint is sound deadening material! Then some of the tuning to get bobbin tension just right after that is a little bit of a pain but once it's there, it's got great tension. I also don't like their tendency to bite me. Once they're set up though, they're nice machines. I guess I just find them high maintenance.