I can't remember, it's been stashed away for about 50 years, I tried it maybe 30 years ago and I remember it just hummed, but I can't remember the tone. A quieter mmmmmmm IIRC. Then I stashed it away and haven't touched it since. In fact, I just now found that it was a 1948 model. I thought my grandparents listened to WWII broadcasts with it all my life. TIL they didn't.
That model has FM, which would have been pretty advanced for the time.
If you do get it out again, it's probably best not to plug it in. That's a transformer set, and if something is shorted you run the risk of destroying something that's ubobtanium.
Here's the Rider's Perpetual Troubleshooter folder for the unit, if you're interested: http://www.nostalgiaair.org/PagesByModel/637/M0013637.pdf
WOW! Lol! Unreal. Just like that you send me the complete trouble shooting manual for my specific model!
I've never tried trouble shooting an old tube radio. I took one apart when I was 5. The plumbers plumbing my folks new house gave me their old beat up work radio (plasic case with tubes circa 1950s) because it stopped working. I was thrilled and curious to tear into it. For some reason I vividly remember that to this day. Anyway, that radio never worked again, lol!
You know a lot more about the old tech tube stuff than I do. Is there any market for a radio like this and a ballpark figure of what might it be worth? As is vs working?
In good condition, there's always some market for a device like this - but I can't really advise you on price, I don't have a feel for what the collectors market demands - I will say the prices you typically would see on eBay and at non-tech shows are probably out of range of what the device is worth. I typically laugh at those prices.
I can give you two things here - the Rider's manual was designed in an era when the device was in use, so you're going to see problems that that manual didn't cover, things that normally wouldn't happen in the device's useful life of 10-20 years. Other things are happening now, parts are corroding, mechanical devices are disintegrating - take the manual with a lot of "the tech using this paper wouldn't have seen this device in it's current condition."
Second, don't plug it in or mess with parts internally if you're unsure. Chances are there are some shorted or leaking (electrical) parts at this point, and you could cause the first tube in the circuit to red-plate (too much current) or worse, burn out that transformer that you'll never find. If you plan on selling it, it's best to sell it "untested, unmolested, will not plug in unless you're paying." That may make some people mad, but I've seen some stuff that probably wasn't helped by plugging in with an unknown state at hand.
That one's a lot more complex than most radios of the time, and it's going to require someone with know-how to physically touch it to try and fix it.