Out of boredom, I decided to remove the dust-cover on my sewing-machine’s crank-assembly to see what it looked like underneath, and maybe clean it up a bit. This was what I found:

The crank-cover is held on by two screws. You can see them lying on the lid of the attachments-compartment under the balance-wheel. The screws are loosened and then the ring-shaped cover is simply slipped off and over the hand-crank to reveal the teeth of the gear-wheel behind it.

This was filled with old gunk and dried oil or grease. So I cleaned it out with some cotton-buds. Then, I put the cover back.

It’s nice to see the workmanship on something as simple as a pair of gear-wheels. The teeth are good and long, so they lock together really well. No chance of the gears slipping and failing to mesh together.