Each individual ball bearing inside the Garrett® dual ball bearing cartridge is held in place by a retainer, and there is one retainer per set of balls: one on the compressor side of the turbo and one on the turbine side. Elevated temperatures can also damage these retainers, which can lead to severe shaft motion (or play), wheels rubbing in housings, and again – catastrophic turbo failure. Keep your bearing retainers happy – don’t over-cook them!