Hello, the motor assembly on my edger has come loose from the deck frame and is rattling around inside. However, I can see that the two screws that hold the motor in place are still threaded into the motor. I have removed the motor cover and have tried to rotate the motor so the screw heads re-engage the keyhole slots, but they need to be loosened first. How does the blade assembly come off so I can do that? Thanks for the help!