My Potterton Profile 60E will not stay fired up. I noticed I had no hot water or heating (luckily its currently summer) & the boiler was not fired up. Feeling the boiler casing it felt warm to indicate it had been on. So I switched the controller to constant & whacked the room thermastat up to see if the boiler would burst into life. Nothing happened. My boiler guage was set to 5, so I moved this up to max. Shortly after the boiler burst into life for roughly 60-90 seconds then went off. I left it for a day whilst I sought advice. Tried again next day, pressed re-set button underside and shortly after the boiler fired up again. Hooray! Ran again for approx 2 mins then cut out again and no life since. Changed PCB approx 3 years ago fror a re-con one. Thought about changing this again. Any ideas please?