Install a good D Cell battery. With the shell off power up the engine. Lock out the E-unit with engine in neutral to keep it from moving. Then with power to engine press the whistle control on your transformer. Make note whether the whistle relay in the engine activates. If it does but no sound then you must determine if it is the relay contacts or the horn.
Trace the wire from the horn back to the relay. Connect a jumper wire at this point. Take a D cell battery and touch one end against the horn and touch the other end of the jumper that you connected to relay contact to the other side of the battery. The horn should sound if it is working. If it does then you have either dirty relay contacts or the battery is not making good connection in the battery holder.
If the horn does not sound with the battery jumper as stated above you can try to shock it by connecting 10 volt AC from transformer directly to the horn. Do this very briefly for only a second or two.
I have only had limited success filing the relay contacts. For best results I dis-assemble the relay and polish the contacts with a 220 grit fiber Dremel wheel.
If the relay does not energize then you must determine if it is the relay or the transformer.
Good luck.
Forest
