turbo max 242e will not aways fire up?

I would go for the air pressure switch, we had a spate of problem switches a couple of years ago which caused the symptoms you describe.
as a temp measure you could try releasing the aps from its mounting so it just dangles on the hoses this normally works.
It is located top right of the boiler, you have to look down the back , no need to take the case off but do turn the power of before doing it.

gary.wright53@googlemail.com
March 2008