you need it serviced, the jet is made of brass and has oil pushed through it at 120psi so over time aperture increases making it richer and richer.you need it oil serviced every year for safety reasons alone
JOHN/ OIL SERVICE ENGINEER, December 2007
check for leak on oil line, even though oil isn't leaking a tiny leak could draw air in. failing that burner may need setting up again with a new nozzle, hope this helps
Darren Pudge, December 2007
There are a couple of things that need to be checked here 1) fuel pump pressure 2) condition of the burner nozzle 3) the cleanliness of the boiler inside. Just because it was serviced recently doesn't mean that all of these jobs were done....!
