I have a Dudley concealed cistern fitted with an Electroflo flush using battery power. The first 'blue' (long) flush of the day, when it's been inactive during the night, often doesn't work properly - the blue light comes on, the motor runs - then there's a 'thump' and everything stops. If I wait until the red light goes out and try again it works fine. I've replaced the green and white flush valve complete, the electronic control box and, in desperation, the actual electronic sensor with the LEDs. No change. Has anyone experienced this - could it be a problem with one of the two air pipes, or the inlet float valve? The 'green' flush works fine every time. Is there a guide somewhere on how to set the adjustments up on these? I know they can be adjusted for more water or less, but I don't know if I need more or less.