this is going to sound like a joke, but it's not.
put the nut back on just covering the end of the shaft. this is to protect the shaft.
sit at the helm and put upward pressure on the wheel with your knees. (or get a helper to pull up on the wheel)
give the shaft a good sharp rap with a hammer.
that'll free it up.
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"The metric system never really caught on in the states. Unless you count the increasing popularity of the nine millimeter bullet." -- d. barry