I'm assuming that your husband is using the rear brake, as opposed to the front. If that's the case, the most likely cause is the plunger in the rear brake switch is hanging up and not retracting to the "open" position. They can be carefully taken apart (pull the rubber boot down) and spray some contact cleaner in there. Then very carefully add a couple of drops of oil or vaseline on the metal plunger rod and maybe a dab inside the rubber boot. See if that frees it up. The other thing that can cause it is that the return spring has stretched a bit and isn't pulling the plunger back to the open position. Hope this helps. Oh, and as a last resort, replaced the brake switch with a new one. They aren't terribly expensive.