Vintage BP John Furniture Credenza/Buffet

Vintage credenza/buffet by B.P. John Furniture Corporation.

I know BP John was based in Portland, Oregon, and stopped making furniture in 1977. The top unfolds lengthwise and functions as a long, buffet style table space. The original knobs are missing, and there are some chips and dings. Other than that, I don't know anything else about it. I would appreciate any information that could help me date it and determine its value. Thank you.