Here is one of those "opps".
This is my Lotus 66-1
While cleaning it, my husband took off the belt guard with the bobbin winder attached. He decided the bobbin winder was so grungy he'd toss it in the sonic cleaner (just water, nothing else in it) and he had a brain lockup and forgot the about the belt guard until after it hit the water. He pulled it out and gave it a wipe, and it was too late.
We've been looking for a replacement for about a year now, and just last night I hit "buy it now" and finally have one on the way!