Since the bulb "appears to be intact", never ever replace it. Never! I know, I know, a 1157 bulb has been in vehicles since my gramma was alive (miss you Stubby McWheezleteets), and only $1, and available everywhere, so it's tempting to just replace it without asking the internet for approval, but if you put in a new one, it may allow an electrical path right back to the battery causing it to get super hot and it will glow so bright you can see it for a very long ways away easily, every time you turn the bike on! Be careful!
As for the horn, the color wrap makes the grounds into a faraday cage and the horn never gets the flow of electrons conversely through the bispherical modulator! Better not push that button anymore, its really creating a boundup pathway for the lightning wires which will get stored in the cells. Cells. Interlinked. The blood black causes nothing to spin and the horn to blow. Furthermore, the pheonixicial flow from the horn button will short to the one stem connection from the horn because of the color wrap. Definitely do NOT look at it to see if the wire is connected, and near EVER put a test light on it and push the button. You may actually find out why and the mystery will forever be broken. Leaving only distain that the reality is far from the intriguing mystery by the lack of effort unmatched in it's emptiness.