Looking for some ideas what may be wrong with my horn on '89 Harley FLHTC, ~111,000+ miles. The horn rarely blows as it should when button is pressed; usually just a faint, short beep and the volt meter deflects down to 5-6 volts. I thought it was the horn so ordered a new one but it does the same thing. Took the horn switch apart, inspected, cleaned re-assembled and no change. If you jumper the horn straight to the battery, it works fine. Thought I would try a different switch from a different circuit; same short beep. Tried a different ground and jumpered to a known good ground; no change. Running out of ideas; any thoughts?