Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Boiler drained and discharged

Observation:

Remove and inspect the DHW filter cartridge. Dismantle the cartridge and inspect the flow regulator and filter gauze.
Note:
Care should be taken to ensure the cartridge is correctly orientated on refitting so that the filter opening is directly above the cold water inlet.
Incorrect positioning can adversely affect the DHW flow rate.