I replaced my seals. Whether I did a good job of it remains to be seen.
You get the old ones out by pulling off the wipers (3 in the drawing above) and removing the retaining clip (4), then yank the fork out of the slider. The seal (5) will come out with the fork.
A bronze bushing (7) is seated in a recess on the bottom of the fork. I didn't change that. Ignore this. It's wrong. The bushing isn't in the recess. Sorry for the mistake.There's a small aluminum cap (11) that fits in a recess in the bottom of the fork. It might come out with the fork tube, then fall on the floor and roll to an inconvenient place, or it might stay at the bottom of the slider. Just be sure it's in the bottom of the fork tube, open end in, small hole out, when you reassemble the fork. A dab of grease on the cap will keep it from falling out while you put things back together.
Slide the old seal off the fork, slide the new one on.
Now this is where it gets tricky. If I were the kind of person who changed fork seals for a living, I'd have a tool that slides down the fork and lets me ram the seal back into place. Or I might have kludged up a piece of pipe or something. Instead, I happend to have ordered an extra pair of washers that go under the seal (6). So I slid the old ones on top of the new seal and used a punch and hammer to tap the seal into place, working bit by bit around the fork, until all the seal was below the groove for the clip (4).
Getting the clip back in requires some coordination and patience. Make sure to push it well into the groove.
Then push the wiper back into place (I got new ones) and you're done.
I got the seals and a crapload of other parts from cheapcycleparts.com. Maybe I should have gotten a fork seal tool from them while I was at it.