The clock has also had issues with mechanical wear; the use of steel ball bearings to support and position the rings has led to grooves being worn into the rings themselves, as the bearings are hardened steel and the rings are not. Some of these bearings have been replaced, as it becomes necessary; the group is considering future solutions to this problem. Other portions of the gear train are mounted on bronze bearings; these are expected to have a shorter wear life and will likely have to be replaced sooner than other gearbox components.