It did work! Thank you!
The other file, which is still broken: http://rpubs.com/briholt/Abnormal_schedule
Is it possible that publishing from different computers could cause this?
My process for the abnormal_schedule was that I would make changes to the markdown file, from my home linux machine, push commits to github. Then at work on a windows machine, would pull the changes, make some edits, commit, push, but then publish from that windows machine. That was about "when" students noticed that the link no longer worked.
For the the getting_started file you just fixed, I think I published from a different linux workspace on my home computer. When I did that, students began to squak that it wasn't working.
I don't know how any of this works, so I'm really just speculating. It could all have been coincidental.
At the time, I began to wonder if the .rpoj file stored the slug, or something.
Thank you for your time and help.