What are these things called?

[Zenger]

Greetings. The machine pictured is my Grafonola C-2, and the parts I have circled are what lock down the motor board. They're just heads -- the bolts are part of the cabinet and poke up through holes in the motorboard. I'd like to find replacements, but I don't even know what they're called. Can anyone tell me? And if you happen to have a pair to sell, please let me know. Thanks!

[Zenger]

Here are a couple of pictures of the bolts they fasten onto. Near as I can tell, they're ¼".

[DanP58]

I always called nuts like that , thumb screw nuts . You can get them online or at hardware store but they won’t be exactly like the originals

[JerryVan]

I always called nuts like that , thumb screw nuts . You can get them online or at hardware store but they won’t be exactly like the originals

Yes. Or just, "thumb nuts". Or maybe, "knurled thumb nuts".

[DanP58]

I also saw them called cap nuts knurled or thumb