I acquired a WTB hub the other day on another of my Pro Flex purchases. Intrigued by the grease guard I just pumped some grease through it. Nothing appeared, then some grimy stuff then clean. Hub now running lovely and smoothly (it wasn't bad before but definitely better now).
It reminded me of the quick regreasing trick with SPDs of partly filling the pedal body with some grease the screwing the axle assembly back in. Always very satisfying.