Hi, I have this boiler in a house I just moved into, for the first week boiler was fine, now it doesn't fire up unless its reset about 4 times, pump comes on, fan comes on, gas valve clicks, but only a tiny flame, then goes out, each time I reset it the flame gets larger,, and as I said on the 4th time it stays on and all is fine till it reaches temperature, then it locks out on flame failure (30 degree light) and again it fires up after 4th reset, it can't be gas valve because it wouldn't start every 4th time, all stats seem fine, I'm wondering is it the combustion chamber gasket, any help appreciated