Wow, I like that, and I hate scale! I'll set something up. From the angle of the photo, it looked like the width of the disk was very narrow (cut-off disk). Yep, keeping the wheel in balance, and running a touch slower would be good if you can. Did I say I hate scale?
The vinegar bath does do some good, it's messy, and the vinegar doesn't last long, so abrading the scale off seems to be the way to go.
Thanks guy!