Reverse Clutch Piston

WARNING: This page is about a different car, the 2003 Nissan Pathfinder. However, it is still accessible from the selected car via links, so may be relevant.

Shake piston to assure that balls are not seized.
Apply compressed air to check ball oil hole opposite the return spring. Make sure there is no air leakage.
Also apply compressed air to oil hole on return spring side to assure that air leaks past ball.

Fig 1: Applying Compressed Air To Check Ball Oil Hole Opposite Return Spring
Courtesy of NISSAN MOTOR CO., U.S.A.