A bad track in a disk device in a data storage system is recovered by determining which cluster in the system the bad track belongs to. Yet further disclosed are related methods of using the assembly. 85 and an Abbe number within a range from 35 to 45, comprising in mass % on oxide basis:. Removal of narrowband noise is accomplished with notch filters that are dynamically adjusted in accordance with a detected noise spectrum. The removable inserts provide the system with the ability to simply, easily and cost effectively change the edge profile of concrete poured against the side form. The second component and the third component are welded to the first component.