Set Appliance State:

Mains Power Off

Observation:

Check venturi test point in the flue air restriction ring for blockage.
Note:
It is not advisable to remove the test point unless absolutely necessary.
The nut that the test point screws into is not captive and it may be difficult to refit both the nut and the test point to the flue ring.
If the test point must be removed, then care should be taken not to drop the nut or the test point as it may be difficult to retrieve.