Hi all, thanks for this great discussion. I had exactly the same problem as Casey, and reading through this thread helped to shape my troubleshooting process. My solution ended up being different (v-wheels were too tight), but this thread helped me get there.
I also needed to clean my v-wheels of some caked-on MDF dust (forgot vacuum once or twice). The dust/gunk was contributing to artificial flat spots in my v-wheels in addition to just adding friction. A toothbrush worked great for scrubbing the v-wheels clean as I rolled them around a full revolution or two, then i took a lint-free rag to the rails. Nice and smooth now!
Shout out also to this week’s Carbide Office Hours video by Winston. He gave a great qualitative description of how tight to get the v-wheels and how easily the carriage should move around by lightly pushing on it. He also plucked his belts so we could hear it, which was great. Anyone in the future with these issues, definitely go check out that video.
This video at Will’s troubleshooting link is also excellent, but I missed it the first time through. The key for me was to tighten the v-wheels just enough that they don’t spin freely. An extra 1/12 of a turn is too far.