Hello- I just purchased a Koken barber chair (#736 I believe) The number below the seat cushion is A250165. Could anyone tell me what that number is (Serial number maybe)? The chair is in good shape, all original. There is only one small tear on the right side seat cushion. There is some rust on it, though. Any ideas on what to use to remove the rust? Could anyone tell me the approx. age of the chair? One last thing, is there a manual or book available about antique barber chairs, specifically Koken, if available? Thanks for any information or ideas.