Nice radio. There are still many TOs floating around. I own more than a dozen, from the earliest Clipper to the last solid-state model.
If you don't already have it, you can download a schematic & owner's manual from:
http://www.transoceanic.nostalgiaair.org/
You should replace the old capacitors for safe and reliable service:
http://antiqueradio.org/recap.htm
For correct knobs, check with Alan Jesperson,
http://www.gn4radios.com/ . He's a Zenith guy and may have a junker/parts set lying around, or be able to supply reproductions.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html