If i hold on to the main rotor tight with one hand and try to spin the main gear clockwise with another hand, this should be locked and not possible to make the turn since the main gear is locked into the main shaft by 2 hex screws. The hex screws are located under the secondary gear. If I remove these 2 screws then lock goes away.

Please make sure these 2 screws are not stripped.

here's another observation: if I spin the main rotor clockwise the secondary gear spin along with it but the main gear doesn't turn because this is the helicopter's autorotation created by the one way bearing.

Andy