The tempo does not change when I operate the tempo slider on the master deck.

To prevent sudden changes in the tempo, if the tempo (BPM) being played on the master deck does not match the tempo corresponding to the position of the tempo slider, the unit is designed so that the tempo does not change until the tempo slider is set to the position corresponding to the currently playing tempo.

Operate the tempo slider in the direction indicated by the LEDs next to the slider. The tempo slider is enabled when it reaches the position corresponding to the playing speed.