Not designed for servicing. You can bend a few of the star-lock washer teeth up with a small screwdriver to relieve the grip and then remove. The washer can normally be reused by bending the teeth down again, but best to order some spares beforehand.
Thank you for your answer. Not sure were I can get some spares of that thing. Do know what it is named? Unfortunately for me, I think/know all old time hardware dealers around me are long gone. Nowadays every thing is prepacked. And the stores is filled by youths. They are polite but know nothing. No more people that know what they are doing. And if they did not have it. They for sure could call up another store that had it. But I i digress
