49-53 mercury flathead oil pump help

[gringo]

replaced the oil pan gasket on my 50 mercury engine and when I did I pulled the oil pump so I could scrape the gasket off, got everything assembled and no oil pressure, pulled it apart and found a lock washer jammed in the oil pump gears, the gear in the block is not turning when cranking the engine, question is what damage has been done and does the pump run off a gear on the cam?

thanks for any help