That is the same model that I have in my living room. I have a web page that shows the restoration I did on mine:
http://www.angelfire.com/electronic2.../porthole2.htm
There is also a copy of the schematic on the page. I have also scanned the factory service manual on similar 1950 chassis. Send me an email or PM with your email address and I'll see if I can send you this file. It is pretty large, I think something around 20MB.