you dont have to remove the top plate to adjust the mesh, just loosen the 4 screws on the bottom that hold the engine. Push the engine so the gears are touching, use your fingers and see if they are fitted tightly, the correct mesh is when there is a tiny bit of play between the gears, you can feel it, just hold one finger on the spur gears and move the clutch bell back and forth, there should be a little play. also the car should roll freely when pushed forward, no binding.