I'm pretty sure the long end goes through to the slip ring so it can wear, the other butts up against the horn push. I get to deal with this next as I need to shorten the brush for my custom wheel. BTW don't play with the brush too much, if you push it in, the spring compresses and the short end slides out, gets hung up going back in sometimes, stresses the wire that connects the two, it breaks and you get to fix it. As me how I know this? (I had to rip it apart to shorten anyway so I don't think it hurt me too bad)
BTW how long is that brush overall?