MTH GG1 horn programing

If you go to the MTH website and enter the SKU number, it will bring up a place that tells you how to reprogram the loco. Basically, it involves putting the loco on the track, powering it up, and raise and lower the throttle eighteen times, then have the throttle about 1/3 of the way up, and push the bell button. It should give a garbled bell sound, then a clear bell sound. Turn the throttle off, and on, it should start and go forward, and everything should work as designed. 

Luke, it's the whistle button for reset, not the bell button.   You do the 18 times and get the three clanks and three dings, then press the whistle button.