[fromthenorthwest]

I would use paper like woodco mentioned, if that doesn't work you could use a worn out sanding sponge or higher grit paper. The sanding scuffs may not be noticeable since it's down low on the flats. If they are noticeable you can always just use a 1-in brush and do those areas by hand again. A good way to eliminate this problem next time is to spray the flats first.