Speaker cutting out at Med/High levels help

I have a pair of ADS M12 that one of the speakers is cutting out the medium and highs sound when I crank up the volume above heavy talking. The speakers then work fine when I lower the volume for a second. They sound wonderfull at lower volumes. They are biamped if that makes a difference.

1) Can this be fixed or do i have to live with this unless I sell them? If so how and How much?
2) Does anyone know the value of these?