I'm thinking you remove the crank handle and use a puller on the castellated sleeve that engages the crank handle (part #76). It's held in place by a Woodruff key and is a very snug fit, IIRC. After that, the graduated dial (79), dial holder sleeve(78), and lock nut (77) will slide right off the shaft. It's early and I've just sat down with the first cup of coffee, so apologies if I'm missing something.
Like Tom, I just cleaned up the knee dial on one of the older shop mills this past week using WD40 and a scrap of Scotchbrite. Worked great and took about a minute and a half. The graduated dial is hard chromed and is not one bit impressed by fine abrasive, especially when wetted with a light solvent like kerosene or WD.
Unscrew the wheel. It is threaded onto a "retainer". Check for thin shims as you remove it so they go back correctly. ALSO, if you take off more than one dial, mark them to go back on the same shaft. I found that the inside depth is different on some than the others. I didn't discover this until AFTER I had removed all of them to clean!!
YIKES!!! I GOOFED!! So sorry, but I neglected to mention that you must first pull off the
castellated nut BEFORE you can unscrew the retaining ring! My apologies. The wonderful diagram (ABOVE) submitted by GH< shows what comes off first. I used a small two jawed puller. came right off.