My 1991 Sportster is giving me a challenge. First, my brake light did not work at all. I replaced the bulb and then the rear brake light switch. That fixed the problem (however, I did notice my front brake light switch also does not light the brake light). All was well for a while, then I noticed my rear light failed. I still had brake lights with the rear brake. This time, I found the bulb had failed. I replaced the bulb and all was well again. Now I noticed I have no brake light again with either the front or rear brake application. I still have rear running lights, just no brake light. I did not check the bulb yet. Any help??