Most likely either the disk is worn, this can happen if fine sand or calcium build up causes it to spin with the drive unit and grind through the silicon rubber. Or, the same can cause the hole in the middle of the drive unit to become elliptical and wobble. You could try swapping the parts between the 6055 and narrow down the cause, usually the disk you could spot just by examining it, the blue rubber under the disk will be like a rubber band instead of a cup. The elliptical hole is hard to spot, but if that is the cause the 6055 drive unit will be silent in the 6095.