XDJ-RX Tracks out of sync

Dear Pioneer,

I own my XDJ-RX for over three years now, which means no more guarantee. First when i bought it, i noticed that when i play tracks, the tracks drift appart rather quickly. I fixed this by DJ'ing through Rekordbox, and sync the tracks (and then unsync) so that they both had the same BPM, so with my laptop i could play. Now to now, i don't have room in my studio for the controller anymore, so now i use it as a standalone in my living room (playing with USB sticks, tracks synced in Rekordbox, adjusted the beatgrid properly). But i'm facing the same problem again... Tbh this really takes the joy out of DJ'ing as i constantly have to readjust,, I'm very dissapointed cause this was a 1600 euro controller for which i payed a lot of money... I really like this problem fixed, because i can't play propper sets on it.