Engine locks up trying to rotate

I have a 1979 beetle in the process of rebuilding it. The engine has not run for a few years. When I try to turn it over it goes so far then locks up, turn it back and it locks up again. I have removed the starter motor as someone suggested I tried that.
Any suggestions, before I go ahead and remove the engine.
Thanks
Any suggestions, before I go ahead and remove the engine.
Thanks
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