I’m trying to determine the age and value of a Koken Barbers chair that my mother-in-law gave me over 20 years ago. The bottom of the seat is stamped No 520A. One portion of the foot assembly is marked 523 A. The chair has been reupholstered by an amateur and needs to be restored. All of the parts works as designed…hydraulics work, headrest goes up and down, leg assembly moves properly and chairs tilts as it is intended to. Thank you in advance for your assistance. Bill