My brake pump has stopped working. I've checked the relays and they're working, and I appear to have 12v at the pump. When I turn the key I get nothing. Unfortunately the lady was driving the truck when it appears to have failed so I don't know what exactly happened. She didn't notice. Any help would be greatly appreciated. Brakes and pump worked great before with only a very sporadic odd sound out of the pump (less than once a month and only 3 times ever). I'd much prefer to not have to purchase a new pump. Is it serviceable?