I have been having a problem with the sound of the horns on my 1966 Metuchen Mustang. If both horns are connected the sound is a terrible discordant noise, more like a squawk. if I disconnect the HI horn, the LO note horn sound fine, likewise, if I disconnect the LO horn, the HI horn sounds as it should. All parts are original to the car: horns, wiring, steering column, steering wheel, horn button etc. Does anyone have any ideas as to what is the problem and how to fix it? Thanks