Why won't the kneading blade/motor shaft on my bread machine turn?

I own a West Bend Hi-Rise dual-blade bread machine. One of the kneading blades turns freely on its shaft; the other one doesn't. I can remove the blades and switch shafts, but that doesn't make any difference. When I grip the wing nut for the stiff shaft on the underside of the bread pan, it still doesn't turn. Can I lubricate the stuck shaft or soak the bread pan somehow to loosen that stuck shaft?