I have a Koken chair model L-33522, this chair is used daily. The chair reclines, spins and will not lock. It will pump up, but will not go down anymore. The last time I had someone work on the chair, he said that it had leather washers. This guy has since passed away. Could you please help me? I don't know how much or what type of lubercant to use, or how to adjust anything, or how to clean the mechanical parts of the chair to keep it in working order. Thanks in advance for any help.