Hi newbie question, I’ve just purchased a VAC SYS SE but not the foot pedal & thought I’d be able to just use it with the in line valve supplied with it, the clamping works on both the base to a surface & the supplied suction plate, but as soon as I put a piece of wood on the suction plate the gauge on the pump jumps into the red & wont move back to green unless I take the wood of the suction plate, any ideas much appreciated.