Boiler installed in 2008. Cannot claim that servicing has been clincally appropriate but had it serviced last year...when strip-down of burner and associated bits was carried out. System failed again earlier this week and local plumber/heating technician called out. He tried to dismantle burner to attempt cleaning but couldn't even get the baffles out! Siezed up 'solid', apparently. Recommended (largely on safety grounds) that whole boiler is replaced. Should I go ahead - or not? Should I expect longer than a 5-year life-span for the beast?