6. Remove the solenoid spring.
7. Screw an M6 cap screw into the solenoid piston to withdraw it from the
solenoid body.
8. Taking care not to damage the piston, hold the flat part of the piston with
a spanner to prevent rotation, then unscrew the M6 x 12 mm cap screw
from the bottom of the piston. This releases the solenoid seal retainer
and valve seal.
9. Discard the old valve seal.
10. Clean all oil and dirt off the components with a clean cloth and check that
the bleed hole is not blocked.
11. While the solenoid is apart, inspect the solenoid piston centre seal and
piston for wear, scratching or damage. Replace piston if required.