[Lindy]

I think that it might be a loss of brake fluid, as the clutch/brake resevoir is low, and now (after my initial post) the clutch is not releasing all of the way (kind of like an on/off transmission in a Bonneville car) and the clutch travel is much less than it was previously, which would explain why the problem got progressively worse on my last drive.

Hopefully this is either a loose bleed valve in the slave cylinder, or an old return line.

We'll see.

Thank you for your responses!