What usually happens is when media blasted without installing a sponge in the opening the media gets in the horn and works its way to the center of the snail. Take them off an tap them on something while hooked to a battery. Turn the adjuster screw back and forth until the start working. Tap them on a hard surface and turn them in the direction to get the dirt out of the snail style funnel. This worked for me a couple of times. you can adjust the tone while doing this.
