Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Appliance drained and discharged
Remove the braided hose bypass pipe, care must be taken not to lose any parts of the internal bypass when removing the hose
Remove the internal bypass valve from the hose / right hand side hydraulic block

Observation:

Inspect the internal bypass valve for contamination and damage.
Ensure there is light spring tension to confirm correct operation.