Yes your correct Beags, Just remembered something else, before I was posted to the sqd. ( 617 ) I worked in MEAS Scampton, and an aircraft was just finishing a check, got told the window boxes where fitted, so dispensed an airman to fit selector boxes. Then when fitted went out with him to functionally check them. ( probraly trouble 4 ) remember that one Beags. Sent airman to right wing complete with dust bin. and selected two on the selector, pressed switch, did you get that I asked, no came the reply, selected five, and pressed, again no came the reply, selected ten and pressed, half way through the dispensing a head appears through the door and asks " do you know you are dropping window out off the left wing onto the hangar floor. oops. right and left selector boxes where next to each other and could easily be cross conected, and being summer both sets of hangar doors where open. Took months to find all the chaff