AF works, but MF doesn't??? Ideas?

Lens is the old 24-85mm USM. The autofocus works perfectly, no issues there. But the manual focus 'skips' when you try and move the focus ring. That's whether it's switched to AF or MF. Move the ring fast, and I may get to catch, but other times moving it slowly gets it to catch. I'm going to open it up, but was wondering if anyone has experienced this before, and what the problem was. It's typically the other way around, so I thought it odd that AF works, but not MF. And no, I won't send it somewhere to be fixed (not worth it).

The "spring" does not put enough pressure on the MF mechanism.
A good explanation with illustrations : http://thingsimdoing.w​ordpress.com …4-5-usm-autofocus-repair/
I have encountered the problem you are describing on another lens and fixed it by increasing the bend in the spring (or washer) like explained in the article.
Its easy to fix if you have the patience to disassemble and reassemble the lens.

That's a great tutorial, thanks. But it (and the additionally referenced repair links) talk about where both AF and MF aren't working. With mine, it's only the MF that's not working. I'm guessing some plastic thing-a-ma-jig that the focus ring moves/moves against is worn down.

It is the same problem with different symptoms. I the spring is too weak, both AF and MF could stop working.

Ok, sounds reasonable. Based on the above, I planned on checking it out, and I hope that's all it is. Sounds like a crazy easy fix. Thanks again!