We tested the resistance across the horn and I think there was...none? Too much? I can't remember, but the owner (who is an electrician) said it was bad. So...my guess is that the horns are blown. His PA unit isn't the greatest either, so I think we're looking at other options for vocals for now.

Speaking of that, I just posted a different question on this in another thread. BUT...thanks to everyone for your help with this.