Noise
My 1947, 221 has the same problem. It has been quieted slightly and it has been to 2 very good SMM. I put tiny rubber "O" rings under the face plate screws, put a Teflon washer under the bobbin and oiled everything I could think of. I even got a service manual.
If there is no end play in the shafts, and there wasn't with mine, then there is one place to oil underneath that is not shown in the owner's manual. The last SMM said it was dry and he oiled it again. I can't see how that could have been so, after lubricating it the day before. He charged $75. It is better, but still not a quiet running machine. I don't know what else to do for the poor baby. They do love oil though. Oh, the place he said wasn't in the manual is called the "cross over" whatever that is. It is on the bottom, near the bobbin though. I just oil everything and then wipe off excess to save the felts. If you need new felts, order them from Sew-Classic.com. That keeps the odor down a little. A bar of deodorant soap, in the box, with the end cut off helps with the Featherweight "Funk" smell. In the end, I am still looking for a complete fix too.