XDJ - RX - Shimering waveforms - tracks not pefectly in sync

Trying to move from traktor on xdj-aero to my buddies' new ndx rj. tracks analysed on rekorbox however i find it near impossible to get the perfect synronization between any two tracks.. with or without sync. i have also noticed that the beat grids from the two tracks as they appear on the display, never seem to align perfectly. they sort of seem to come near parallel in the center only to drift apart towards the left end of the display.... sounds really off too!!