To make access easier while changing the fuel filter, remove the Air Filter and cover. Cover this aperture to ensure no debris falls in while carrying out the work.
The above illustration shows the securing bolt, which requires unscrewing to change the filter cannister. When unscrewed, the bottom falls apart. Ensure you have a container under the filter to retain the diesel spillage.
Having changed the filter, keep pressing the priming button until pressure is felt. You will find when starting the engine it might cut out. Pause for a short time and press the priming button again. Then restart with 3/4 position of the throttle.
When screwing up the retainer bolt, hold and place the bottom retainer in a position convenient for the water drain.
Mine can be seen at the back!