Hi I have the same boiler and had simular problems It could be that their is an air lock in the system like I have. One important thing to check is that you do not have water dripping out of your emergency out let pipe outside (this is the copper pipe that appears outside) as the valve sometimes gets stuck open with limescale. The best and only engineer I could find was John Dribble M 07981300004 if he does nt answer leave a message and he ll call you back. He was the guy who designed the boiler in first place and used to work for Maxol. Dont listen to BG or anyone else who tell you the parts are not available as they are. an y other Q's email me on as i ve fixed my boiler quite a few time
Ian
March 2010
Automatic Answer
We may have found other answers which could help you.