Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Remove fan & burner assembly
Refit rectification electrode if you have not already done so

Observation:

Check the burner is not restricted or blocked and is in good overall condition.
Check that the rectification electrode is not warped or distorted.
The gap between the rectification electrode and the burner should be approximately 7mm.
Note:
Ensure all disturbed seals and washers
are in good condition on reassembly.
Refer to ADAPT for replacement advise.