Solenoid most likely locked on causing the sleeve to melt. No, there is not a switch that reads the position of the diverter. The ball is staged and the software looks for the ball to stage in the subway. It leaves the diverter solenoid on for a short time and looks for the ball to arrive in the cannon trough. Just loosen that Allen screw to take the diverter apart and clean. It's been a long time since I owned STTNG so I'm not sure if you will need to remove the subway ramp or not.