Starter Box
I agree with pre-heating the engine.
I would not bang on the flywheel as it might put flat spots on the connecting rod bushing. Maybe lite taps, but not a big one.
Also, you can try putting a small drop of oil around the top edge of the piston so when it goes up, there is something for the piston to ride on and not just metal on metal.
Also, I have an ofna starterbox. Chrome top with the single large motor.
That thing (with a good battery) seems to turn over the most stubborn
new/tight pinched engines.
I have a couple of new RD Logics which I have not tried yet.
Yellow top. (IF anyone can comment on them, please feel free.)