This is applicable to 337 G & H models with the lever-type parking brake handle.
The service manual and the parts manual have no procedures to rebuild the parking brake valve. So my buddy dared me to open it up and see if it's rebuild-able. It is, with standard o-rings suitable for 5606 fluid.
Use Service manual procedures to remove the valve from the aircraft.
Remove two lower hydraulic fittings, exposing valves, rods and springs. Remove circlip from cam lever and pull cam out. Replace 7 o-rings and re-assemble in reverse order, then reinstall in aircraft per service manual.
Good wrenching!
