RE: Stiff Flywheel on a new engine
The engine sounds like its dry, Try putting a little After Run Oil into cyclinder and down carb. or some other very light oils and turn like you did before with screw driver. This should help you turn the engine over better. When you go to start engine leave the glow plug a little loose for first little bit that will help as well. Good Luck hope this helps some.
Lightnen