my customer has a boiler thats 7 years old never been serviced, two weeks ago the fan went. so i replaced the boiler fan and serviced the boiler, replace gasket etc... put everything back together. fan runs, pump runs, gas valve opened and sparking but it just not igniting. but after i have turn the boiler on and off so many times it started up. Today i got a call from this customer he said when he put the 24 hour mechanical timer on timed boiler will not come and different fault codes have showed up, first time it shows F1, second time it shows F3, third time it shows F13. everytime he has to turn the boiler off then back on, and the boiler fires up. any ideas????