Mechanical transmission losses account for a significant portion of energy dissipation in electromechanical actuators. These actuators generally use a combination of high-speed electrical motors with a high-ratio gearbox. For such high-ratio gear transmission, even minor deviations in meshing can lead to substantial power loss. To mitigate this, rollers can be used as redundant elements along with gears. This paper highlights the importance of such redundant rollers that function in tandem with gears to facilitate optimal gear meshing through a specific gearbox design which enables to asses the contribution of rollers and gears individually and in combined manner. The findings reveal that overall, rollers significantly reduce gearbox losses both under no-load and loaded conditions. Especially at high speed and high torque regimes, where the gearbox usually suffers severe losses, the efficiency remains consistently high due to improved meshing.