I've posted this for anyone that's has similar boiler (installed 1993) to highlight my experience. I've been wrestling with intermittent lockout for last few weekends (I work away from home). Must admit boiler hadn't been serviced for a couple of years. I normally do the basics myself. As it was overdue for service, and on inspecting parts I have this time replaced; main filter, flexible hose (kinked), nozzle (very sooty), electrodes & leads. I had noticed pressure fluctuations on water system guage so also replaced expansion vessel (confirmed perforated on removal). I have tried a new control box (old one doesn't appear to be faulty) and fitted new oil pump (previously replaced 2 years into boiler life due to failed internal key drive). I have cleaned out the combustion chamber thoroughly as very sooty and set up burner/nozzle assembly to correct distances iaw manual/instructions (noticed nozzle assembly retaining grub screw was slack and I suspect distances were way out). The boiler will now fire up and runs great, cutting out as normal once temperature is reached. On subsequent demand for heat there is a buzzing noise and the motor does not turn (also noticed it is hot to touch) and boiler lockout occurs shortly thereafter. If I then wait for the control box to reset, I can then clear lockout by simply pushing button & this time the motor starts normally & the boiler fires up & runs until heat is reached. The only question running though my mind is whether I try to replace the capacitor or just bite the bullet and replace the motor again(approx £38 +p&p)? I remember replacing motor circa 1999/2000 (do they only last 7-8 years). Before anyone asks why I haven't had an engineer out, I live outwith the big cities and they appear to be reluctant to visit. And no I don't have relatives playing banjos on the porch!
