The matter of the garage-sink drain having risen in priority of late, I decided it was time to Deal With It. It had been draining quite slowly for some time, and snaking it out couldn't be that much trouble, could it?
Disconnect wobbly plastic sink's wobbly plastic flexi-drain from the rigid plumbing. Poke rigid plumbing with cheapie household snake. Seems to be OK up to the point the snake doesn't want to go further around the bend. Hm.
Unscrew cleanout plug* between bend and wall. Poke snake at bend from that side. Same thing, and between the two attempts, I'm pretty well convinced that the bend is clear, so it's not an accumulation of sand and gravel causing the problem**.
Next: poke the snake the other way, on beyond the wall. It goes in a fair way easily, then hits some kind of squidgy obstruction. Eureka? Pull it back out with a glob of ick. Repeat, with various wiggling and turning. Stop getting ick, but the snake now hits a hard obstruction.
Oh, well. Obstruction could be junction, no? Put the plug back in and run some water.
Nope. Drainage has now gone from slow to virtually nonexistent, apparently dominated by a slow leak into the bucket under the drain.
Guess I need to call a real plumber, perhaps Monday afternoon, in among all the other Stuff I Gotta Do (Monday through Wednesday have cluttered schedules already).
Plumbers are expensive, though. Maybe I'll make a hardware-store run in search of a shorter, better-configured snake? Don't need more'n 4 feet, and having a decent handle for turning it, and less of a tail getting underfoot, might just make enough of a difference.
Update: Off to Home Despot; look at snakes; end up with a Kwik-Spin. Good thing I got something fairly long; after several more probulization cycles, I stopped getting wads of ick 10 feet or so down the pipe. Actually being able to turn the thing was a big help (the auto-feed feature, not so much in this particular case).
Put the plug back in: it drains properly now! Good as new!
I didn't try very hard to identify the fibrous component of the ick, but feathers from cage-cleaning over the years would seem the obvious suspect.
One cool shower later, I'm feeling almost human again. Almost.
And I haven't managed to get the smell off my hands yet. Maybe baking soda will help. Or bleach. Or nitric acid. Or maybe I should use the time machine and tell myself to have broken out the nitrile gloves.
But, hey: $30 for a snake beats $300*** for a Silicon Valley plumber.
* Maybe not intended as such; it could have been the place a washing-machine drain would have connected, had any inhabitant of this house ever owned a washing machine.
** Come to think of it, I believe I'd removed the bend sometime last year and removed such dense crud as had accumulated: dirt, sand, brass, swarf, and whatnot. So it should have been obvious that the current blockage was downstream.
*** Or however much the neighbors spent having their drain pipes totally re-done, including reaming out the crawlspace to accommodate modern American plumbers. I think bringing in a team of Cambodian plumbers on H-1B visas might have been cheaper.