The quick fix is press the magnets back to close to the membrane. You can do this on the pad side magnets but not the other side (you have to remove the grill, the damping, and a cardboard to reach the magnets).Very interesting... Have you figured out a simple fix or are you also sending them back??? Only very few of us are experiencing this issue.... My left driver works perfectly 100% of the time... It's the right driver that I have to tap on the grill a few times and then it works perfectly for my whole listening session of 3-5 hours.
And this fix is only temporary. The opposite sides of magnets will repulse themselve away from the membrane. This depends on how big the gap between the baffle and the membrane holder. And this gap may becomes bigger and bigger because the plastic baffle will be bended by the continue magnetic repulsive force.
I have the problem on left side when open box. Now both.
This is difficult to explain by words. If there are more people have this problem. I will draw a diagram to show how this problem caused. But of course if Garuspik can tell us the truth is great.