SO I start the old 78 this morning, and the charge light is on. And I hear rattling. So I pop the hood, and one of the crank pulleys is loose. The first one, that drives the water pump and alternator. I can wabble it around, behind the ac pulley. So what do I do?? Do I need a new pulley assembly?? Is this expensive?? Thanks. The pulley still turns the pump and alt, but barely.