Combi Boiler - pilot will not light

[orange]

I have a Worcester 9.24 BF combi which uses a Honeywell V4600C valve.
Recently the boiler has started cutting out during hot water demand. It has always been possible to relight the pilot if the boiler was left off demand for a few minutes. Now it has cut out and the pilot will not light, there is no problem with the spark but it is as if there is no gas reaching the pilot.

Help please.

 

[ChrisR]

Make sure the gas valve knob is in the right position for ignition.
Make sure you hold it for enough time fot gas to accumulate in the pilot pipe - a few seconds should be fine.

Pilot jet could be blocked, of course.
It's usually sludge which causes overheat on HW drawoff.

 

[orange]

Thanks for the reply, I managed to get the pilot going again after about 3 hrs of trying. I think the pilot jet was blocked and may still have some problems lying in wait. I managed to work out where the screw adjustment was for the pilot inlet and wound it right in and back out a couple of times and managed to get it lit after.

Can you recommend any techniques for getting rid of sludge which doesn't involve a gas repair man?