Present work goal is the know-how acquisition of structure and operation of an NVH test bench for Stellantis transmissions, with the aim of building its Quality Maintenance system by applying the 7 Steps of Quality Control Pillar (WCM). Throughout the study, two main benches' chronic loss factors are detected and faced: - Bearings overheating on "primary shaft" group; - Tripods joint unscrewing and elastic joint breakage on "secondary shafts" group. In both cases the Advanced Kaizen tool is implemented to analyse the issues, to verify the system according to the State of Art, and finally to make proposals of alternative layouts, in order to eradicate the loss factors.