I have a Proto 2000 Heritage Berkshire 2-8-4 with factory installed QSI sound. I operate the engine with the MRC Black Box. The bell has stopped working properly. When the engine is in neutral I can turn the bell on and off. When the engine is moving, I can neither turn the bell on, nor turn it off if I started it ringing when the engine was in neutral. If I operate the engine on straight DC with the Quantum Engineer, the bell works properly. Also, I note that the engine on the Black Box also now has a top speed of only 45 smph whereas on straight DC with the Quantum Engineer the top speed is in excess of 65 smph. I have tried many resets to no avail. Any ideas as to what is wrong and how I can fix it?