Just to update everyone.
I have pulled the pcb board (or the case that its in) out slighty and away from the bottom of the bolier and it works fine.
I am guessing that when the boiler build up heats, it is effecting something around the PCB board, or even air flow sensor which is on the back...
This didn;t work.
I have noticed a few more thinks.
The boiler seems to start up fine when cold. then when it gets hot it stops and doesn't turn on again, even when it gets cold again.
I took the front cover off, moved the pcb and turn it back on and it worked.
Reading into a few of the...
My ideal classic normally works ok, but sometimes it just won't light.
I can hear it click when it turns on, I can hear it click when I move the thermostate, but it just won't light.
The only thing that does make it work sometimes is when I hit the front of it.
It seem that the boiler...