10 month old Bosch fuel pump, I believe. Only about 3 hours run time. i have it parked at work. The last time that I let it sit, I banged the tank a little and the pump loosened. This time I let it sit for a few months and It stuck. I banged the tank a lot and nothing. I 'm guessing the gas gummed up the rotor. Can I add a strong dose of an additive to loosen up pump? I don't want to go through the hassle of dropping tank again. Thanks.