Does anyone have any experience with intermittent buttons on the Zonemaster II? I have one button that clicks, but doesn't actually do anything unless you push on the upper right corner of the button. Obviously, the simplest solution would be to send it back to RH Designs for repair, but it's about 8 months past the warranty expiration and I want to make sure there is nothing I can do to repair it myself. I really don't want to send it back to the UK for repair and be without the meter for weeks if I can avoid it. Membrane keyboards are common and there is some info about repairing them on the web, but I'd be interested in hearing of anyone has actually repaired the keypad on the Zonemaster II.