Tractor Repair: siezed engine, thanks art, fan belt

Question
tractor is a farmall M  made 1940.  has not been run for many years due to unrelated radiator damage and use of other tractor  .. usually turned engine by fan and fan belt.  this time  after the winter it seemed solidly in place tryed a bar thru the crank extension at front but it was still stuck..  your suggestions to get it unstuck without taking head off?? what  to try  ??? thanks   art

Answer
I have found that if you  remove the sparkplugs and pour Automatic transmission into each cylinder and after about a week try turning the engine by a hand a little each day until it frees up.
I have used this method on engines that have locked up after 6-7 years of sitting.
Let me know what you find out.
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