uh,.. I don't think they're standard, so you may be out of luck on the Kohler unless you find a German or Kohler handcrank. I have the same problem finding information on the Winselmann that I have.
You'd be hard pressed to put a Singer hand crank on the VS2. The handcranks typically use the motor mount, and both the VS2 and the model 27 that replaced it predate the motor mount. Hmmm,.. that seems to mean that any Singer prior to about 1913 can't be hand cranked? Can anyone confirm that?
I'd sure love to hear if there's another solution though.