Just bought a legend se. It's probably around ten years old. Been working fine til the other day. Last two jobs pressure would drop at the wand after pulling trigger 15 20 seconds. Drops about 30 percent. After I do dry strokes and then pull trigger again it starts out fine but once again it starts to drop pressure after about 20 seconds.pressure registers fine at machine. Could it be bladder tank? It's like it just needs a few seconds to build back pressure when not pulling trigger but begins to drop pressure a few seconds after pulling trigger and slowly gets worse. Any ideas greatly appreciated!