I bought a used PF410 Ameg 4 x 10 cab. I like the cab and the sound but noticed that it came to me with the 1" horn not functioning. It is an 800 watt - 8 ohm cab. How can you tell if the crossover is fried or if the horn is fried. I have seen both happen over the years. I try to be a DIY guy when I can. Thank You.