"By "lower crank seal"
"By "lower crank seal" do you mean the the gasket between the engine body and the oil sump? When I took mine apart I removed the lower gear unit (propeller head) and the vertical drive shaft (from propeller head to the engine) all in one piece. The shaft remained connected to the propeller head but slid out of the bottom of the motor. The drive shaft passes thru the botton of the engine housing and is splined into the engine itself. There were no keepers or threads of any kind, the splines on the shaft just meshed with the splines on the bottom of the motor, basically a "slip joint". There is a rubber seal as the shaft enters the motor which might provide some resistance but the shaft will just slide thru the seal. Like I said when I removed my propeller head I tapped on one of the fins with a hammer and a piece of wood and the vertical drive shaft came loose of the motor end and stayed connected to the propeller head. I did not study how the shaft was connected to the propeller head but maybe it is also just a spline connection and I got lucky and the connection at the motor came loose first, which for me was great because that was what I was after. If your vertical drive shaft remains "stuck" in the motor then I think the suggestion pilotart gave above sounds like a good way to unstuck it from the bottom of the engine."
