Rayburn 480k cutting out

[22sbtr]

My Rayburn 480k works fine on the boiler side but the cooker heats up though not fully cuts out and after about 20 seconds starts up again, it then continues to do this. Have replaced photocells, two different thermostats, oil pump and motor and it still does it - any suggestions

 

[Exedon]

They always were a problem cooker especially on cooker side,
Which burner is fitted to yours?

 

[22sbtr]

It’s an eco flame?