First, can you rotate the cover, and if so, does the crankshaft rotate when you do? If so, the crankshaft is frozen to the seal or the cover. Was the engine capable of rotating before you started dismantling the mower?
Second, you gave the engine manufacturing code earlier, so I knew it was 1974. My similar engine (60102) was made in 1963. That engine model has been around a while.
