aim valve manifold malfunction?

well, i have an s-10 with the aim valve manifold and as of recently my driverside rear will not go down, when i dump it, it wont dump but i can hear air leaking out of the fill. so i tried totally emptying the tank and of course it went down, but it still had air in it when all of the others were empty. so then i filled the tank back up and it didnt fill up like the fill was stuck, but as soon as i flipped the switch it went up and would not come back down. any help on this would be greatly appreciated as it is my daily driver.