i just bought a used 52mm mechanical greddy boost gauge. the backlight work, but it won't read anything.. the needle sits past 2.0 bar when the car is off, at idle and even when i am driving it won't even flinch.. doesn't move no matter what i tried. i made sure all the wires were ok and i checked the boost sensor thingy for leaks but i couldn't hear anything.. any suggestions??