had the same problem, remove the front, behind this you will see the burner box housing, it has 4 spring clips and 2 screws , remove these and take of the cover, to the left of the burner box you will see a pipe
with 2 sensors on it , the top sensor has 2 connectors
to it in between these connectors there it a small button ,press this and it should click in. re-assemble
the casing and reset the boiler (switch with flame).
the boiler should now ignite..
the small switch was the overheat trip..
Carl
carl
November 2008