can anyone help on this fault that i've had on a potterton profile 50 e, boiler will fire up run up to temperature most time, click off then come back on after a correct period which is fine ,but once in a while it will light up run for 5 mins then, cut out (main burner goes out) pilot stays on (but its auto version) the gas valve has been replaced by myself yesterday & set up correctly 12.5mb & gas rate 18.21kw, the only thing i can think off is a loose connection on pcb ect as pilot solenoid has 237v and main burner solenoid nothing when fault happends,but has 237 when boiler runs fine, i also get a clonking at main burner solenoid when fault happens, any suggestions ??