Picked up a non-runner really cheap today. I was assured that the engine was not seized but that there was no compression and it needs new rings. Now that it gets here I find that I can't turn the engine over with or without the clutch in. It was opened up 6 months ago and all the engine screws are hand tight so pretty sure the oil has been drained.

Is there any chance that something other than complete engine failure is not allowing rotation?