Negative. Was only small debris in the trap. Gotta be the horizontal pipe or more likely below.
What I do know is that draining the kitchen sink above causes water to back up in the basement sink.
Discussion
Ooo that’s a good insight. And less accessible on one’s own. The basement sink filling is a clue that the blockage is in a pipe that is common to both of them. Have you tried a drain snake? I’d use it from the bottom sink
I don't have a drain snake. That may be worth buying just to have on hand
Don't think I can get past the 90 degree turns here though. I kinda want that horizontal run replaced with PVC. While I doubt it's the ultimate cause of the problem I would not be surprised if it's severely corroded inside leaving little drainage
It seems like we’ve gotten past the easier stuff.
I think I’d try the snake still, it should make it past the 90 degree bend, but also exactly how much you want to or have time to try before letting a pro handle it is an individual thing so I respect that.
I've got an appointment with a plumbing company coming tomorrow morning.