There is a formed steal band inside the handle in the shape of a tear drop, this acts almost as a spring which springs over a bump on the crank lever where the handle fits. Something is worn or the spring is sprung. maybe some shiming in the handle is in order. The tear shapped spring thingy acts as the bearing surface within the handle which keeps the wood from wearing and has to be forced on and off the crank.

I am recalling this from a while back, I have a machine which looses the handle if the operator is to vigorious. My discription is how the handle on this machine looks and works, yours may be different.

I would say the handles were dry when fitted and they just dryed a little more in addition to the wear they recieve.

Tim