So I'm covered in saw dust, or rather sander dust. Good grief. My wife may never forgive me.
I spent a good 1-2 hours tonight truing up the drum. I simply used a piece of flat wood, on top of the adjustable table, to which I had stapled some sand paper. I've still got a number of low spots, but I feel confident they'll come out in the next day or two.
Turns out the dimmer switch is probably just not necessary. I pretty much had it wide open the entire time. I think the drum is turning at roughly the right speed. I don't think the motor is able to turn the whole thing at it's full RPM capacity. Though, I didn't smell any cooking electronics during the whole affair, and I actually pushed the motor pretty hard. Several 5-10 minute sessions without giving the motor a break.
And, the drum ran straight, no wobbling. at least, none once some of the bigger irregularities were sanded off. They did initially make for some decent wobble. Once they were gone, it runs steady. I feel certain it will result in some pretty consistent thicknesses once I'm actually sanding wood on it.
The drum was solid on the shaft as well. If the shaft was turning, so was the drum.