ariston ignition lockout

Hi guys

I have an ariston microgenus 27 mffi, installed getting on for 10 years ago.
Recently it has started to lockout due to ignition failure, it relights fine on reset, but is starting to become more frequent and inconvienient.It is now locking out about twice aday.
Has anyone any ideas, before I call out an engineer and he starts bull5h1tting me, my initial thoughts were maybe the gas valve but any more pointers would be gratefully recieved.

Cheers
Gareth

Could be gas valve, but then again, it could well be something else, you need a RGI so ask friends for recommendations, and ask for no fix no fee.

cheers mate