Okay, so a couple of weeks ago my grandma let me at my grandpa's old stash of goodies from when he was an engineer for bell labs way back when. The best of the loot was this puppy.
Essentially it just generates tones. You can set it to square or sine, and then pick basically any frequency. At one point in the vid the frequency goes above human hearing, so it drops out.

I want to turn the thing into some useful musical instrument. Maybe get it hooked into an effects loop or something

So here's my problem: I know nothing about how to mod this thing. I had to rip open a wire from an old speaker system to attach to the two nodey things so i can get sounds, but idk how to get it to a quarter inch cable. Also, the sound gets all scratchy and crappy when the nob goes anywhere between 6 o'clock and 10 o'clock.

Help plz?
It's function generator, not a guitar effect... tbh I think it's a bad idea to try to make it one. what are you even going to need a droning tone for, anyway? Imo it's too complicated a procedure for such a minimal result.

My advice is to keep it as-is, or at least sell it to someone who could get some use out of it, like a bench tech or something. I'd kill for one of those old things.
i'm not saying I would run it as an effect, I'm saying i would run effects through it. Because of the knob, you get a cool slidey effect when you jump from note to note, so you can still play melodies through it. I wouldn't just let it drone,
so what exactly are you trying to do? like change the output jack to suit a guitar cable? that would be fairly simple actually. heck, depending on what it looks like exactly, you could maybe just use an adapter. im not sure i would do much physical modding to the thing itself, but there are a few other things you could maybe do outside the box. maybe just run some effects after it or whatever

if you do open it, maybe you could put in something is basicly like a feedback loop. so the output runs back to the input, but allow you to put an effect in. depending on how the signal is generated that may not be possible. heck, its hard to know what the heck you could even do to it without knowing how it generates the tones.