Hi!
All of us that has seen a experienced old gunky Castor oil clad engine bearings know that this is the fault!
Just take the engine apart and get rid of those nasty bearings! It's so easy to do! Cleaning is no option when it looks so bad as it does in the pictures.

What's happening when you turn the crankshaft now is that the balls in the ball bearing stand still and the axle glides only on the inner ring surface, or try to glide on the inner ball bearing surface (Which it cannot do due to all that old gunky Castor oil)!