I just bought a house with an old boiler. Whenever it turns on it makes a very loud buzzing sound. I have located the source of the sound coming from a small compartment on the side with a small coil of copper wire. When I had the gas turned on back in the summer, the gas man told me the buzzing was coming from corroded connections and all I had to do was file the connections a little bit. Now I can't see where to do this filing. Or should I get something replaced?