Thanks for the replies. Of course a cla is always a good idea with an old crusty camera, and a bath in lighter fluid did bring my self-timer back to life, but it didn't help the issue with 1, 1/2, and 1/4 seconds.
I've taken someone else's images of the mechanism and made some marks on them to discribe what is happening.
The tab (orange circle in the picture of the escapement) should move into the notch (orange circle in the image of the "cam") in the direction of the green arrows when set to the speeds noted above. It will not do this on its own though. If I cock the shutter and it is in timer mode, I have time to place light pressure on this tab when the shutter fires. When I do this, voila, the tab goes where it should and I get a resonable facsimilie of whichever of those speeds I've chosen.
Unfortunately it only does this when I push on it. Which leads me to believe that there's a spring either missing, broken, or not engaged with something.
Any chance someone knows this shutter well enough to tell me where to start my search?