To elaborate on what Tony has said.
You need a full service to the boiler, this involves removing and cleaning the burner.
Consider a BG technicians role, he/she visits sveral boilers in one day and each may be of a different manufacturer or model. He/she cant possibly know all these boilers so, he/she gets out the laptop and follows basic dianostics, now due to the time limits pushed upon him/her will restrict the depth they might go to diagnose faults.
By the way Im not BG Iam independent.
What you have is a dirty burner, once cleaned all will be well.
With all the parts thrown at it you have a nearly new boiler to boot.
You need a full service to the boiler, this involves removing and cleaning the burner.
Consider a BG technicians role, he/she visits sveral boilers in one day and each may be of a different manufacturer or model. He/she cant possibly know all these boilers so, he/she gets out the laptop and follows basic dianostics, now due to the time limits pushed upon him/her will restrict the depth they might go to diagnose faults.
By the way Im not BG Iam independent.
What you have is a dirty burner, once cleaned all will be well.
With all the parts thrown at it you have a nearly new boiler to boot.