[amcf18]

Did you confim that the gear on the starter is spinning? You say it is a new starter. Did you change it?

 

[amcf18]

Starters can run backwards, if they have the wrong pickup in them.That would cause your one way to free wheel. If the one way is turning the right way, it should be turning the engine over via gears. If one gear is not turning in that sequence, you have found the problem. if the flywheel is turning and not the engine, it has to be a sheared key.