With a bit of hunting, almost certainly episode 22, 'The Chosen Path''The Chosen Path', of Lightspeed Rescue, originally shown in 2000. The blue ranger in this series is Chad Lee, played by Thai actor Michael Chaturantabut. A large focus of the episode is the interaction with his former Sensei.
The scene you refer to matches the screen capture below, and occurs at 15:10 in the linked YouTube video.