So earlier I mentioned that I pulled the stock Delco Remy 12V horn off the coach and prepared it for repair. Turns out that the only issue (other than looking rough) was that the internal point-gap was dirty.
Cleaned this with a piece of paper and all is well and working again. No adjustment needed.
The goal is to sand-blast it (plugging the outlet) and either clear coating or painting to protect. Should help improve the sound too.
Until next time,