Hello and welcome!
Ron or Chuck can verify there was a back on the set. Is your set a console (floor standing) or a tombstone table model?
I know that some online sellers are thrilled of having a set make noise and claim "it works!!" Some Ebayers say a radio has been 'restored' I would be suspicious of these claims until I made an inspection under the chassis myself. We have seen some real hack jobs under the chassis. That can be dangerous or even a fire hazard.
It may work for a while, but if it has original parts inside, you may be on borrowed time. Those 71 year old parts have probably dried out, and if they short out or fail, they can quickly take out an expensive transformer. The noise you mention could be a dirty control, or a bad capacitor.
I don't know your background, so you may not understand about the circuits and why capacitors should be replaced before powering up. We don't want to hear that your set burned up or worse.
Have a quick read here:
http://www.philcoradio.com/tech/plugin.htm
Even though a radio picks up stations, (that IS a good sign that other parts are working) I would not use it until someone can replace the filter capacitors. You will have a safer, and long lasting set that way.
If you are good with a soldering iron and can even slightly read a wiring diagram, you should be able to replace the parts yourself.
The Select a Tenna should work to bring in stations, but I'd do the recap first as it may bring in a lot more than it is now. The loop antenna will be able to null out stations to the side of your target area.
Good luck!
Gary.