Another time travel story, I think it was “young adult” age group. A student visits his uncle who has built a time machine in the basement. He’s demonstrating the controls to the boy when something calls him upstairs. There’s an earthquake and the boy is thrown against the controls, and the ship is flung into the far past. I think he has adventures encountering Neanderthals and Cro-Magnon humans before he is able to figure out how to set the controls to get him home again.
That’s the puppy! Thank you.
My favorite story of a deep mysterious hole is “Hey You Down There”
That reminds me a little of Tunnel Through Time (Tunnel Through Time - Wikipedia) but it’s not quite a match. There was a collection of stories about Boy Scouts with a time machine too Time Machine series - Wikipedia
That sounds kind of familiar (there’s a story about aliens disguised as razor blades - but that’s clearly a different tale).
How about Terry Bisson’s “The Hole in the Hole” The Hole in the Hole by Terry Bisson : Clarkesworld Magazine – Science Fiction & Fantasy
That was fun; but it’s very definitely not the story I remember.
I suspect I’m remembering the Bujold suggested a few posts above…
But what’s she going to send them for an encore?
Well, just suppose Donald Trump heard there were gold bars down there. And they did want turkey!
Interesting because a lot of places built before the 70s has razor disposal slots where the razor would just drop int the wall
I never realized there was an original short story for that. I remember that when the Amazing Stories episode aired one of my middle-school teachers loved it so much that he wheeled in a VCR and showed it to our class. (No, it had nothing whatsoever to do with a lesson.)
A “summoning a demon” short story, which I can’t find because my searches return too many other examples. The one I’m thinking of is a researcher (college student?) studying medieval traditions of demon summoning figures out that all written accounts of how to do it have a crucial step deliberately falsified (the summoning pentacle has to be inscribed vertically on a wall, not the floor). When he tries the corrected ritual to his astonishment he actually gets a demon. Who then informs him that he’s forfeited his soul in exchange for one wish. The summoner wishes for time to frozen for one hour, which gives him enough time to come up with a way to get of the dilemma: he redraws the pentacle on the demon’s stomach, so its attempts to remanifest lead to it shrinking away to nothing.
Convergent Series, Larry Niven
You beat me to it - good job
One of my proudest SDMB moments 
Jeez, I might have asked for more than just an hour.
I’d misremembered; the wish was to stop time, but the demon would come for him regardless after 24 hours of subjective time.
Sci-Fi novel written in 70s/80s I think.
Primitive aliens arrive to conquer Earth via a series of portals/wormholes. America/Russia/Europe are able to easily beat them due to a technology advantage but they’re still INCREDIBLY annoying since they can pop up anywhere. The major superpowers realize a much smarter alien race is controlling the portals but aren’t paying that much attention as every single time a portal invasion is defeated they just manifest a new one somewhere else but using the exact same tactics. Eventually scientists discover how to hijack the portals but they realize that permanently closing them or having the aliens just get dumped into the ocean might cause the alien controllers to finally wisen up and start doing much worse things. So the temporary solution is to literally just open up the portals in random places in the Middle East/China and just have them deal with it with their numbers (and also neutralize them to the Western powers benefit) and if they get overwhelmed just start nuking them. The book ends with the Iraqi Army fighting the aliens as an American scientist humorously muses that the Iraqis have a number of years left before the aliens overwhelm them and by then maybe they’d figure out how exactly to deal with the alien masters.
John Ringo - Into the Looking Glass
That was it, thanks! Lot more recent than I remembered.