There are two cast iron sealing rings on the cranks large rotary valve and since your motor shows signs of moisture having been in it, they are probably stuck to the crank, just like piston rings stick to cylinder walls from rust. Soaking with your favorite penetrating oil should help break them free.
In this photo you can see the grooves in the large bronze bearing which the sealing rings fit in and why they require an 8:1 fuel mix.
