I don't usually find it necessary. You might try a used dryer sheet, then run a hopper of Unique through it. If it's going to pick up graphite, Unique will do the job. One thing to remember is to clean the cut-off bushing every now and then. If you pull the screw out of the handle assembly and pull the drum apart, you'll see a white bushing in there. This gets caked with graphite and can cause variances with smaller powders.
Also, adjusting the tension on that screw can help prevent the drum leaking or binding on powders such as AA#2, which are like fine sand and get everywhere, stopping up the works. Tighten it a bit for finer powders. Normal use should be firm, but not hard to work.