Sunroof drain tubes clogged

Not an M related but my other car's front drain tubes are clogged: when it rains the front of the headliner/a pillar get wet and drips and floor always gets soaked, I've poured water down the track and back two work fine, but the front two drain very slowly, how do I fix this, neither my Diplomat or Legend (my only other sunroof cars) had this issue
Author: Mopardan