The ME-25's expression pedal has been set for optimal operation at the factory. After extended use the pedal may need to be calibrated.
Here's how to calibrate it.
1. With the ME-25 powered on, press and hold the EXIT button and then press the SOLO pedal.
2. Release EXIT and the SOLO pedal.
3. Move the EXP pedal all the way to the heel-back position until it stops, and then press the WRITE button.
4. Move the EXP pedal toe-forward all the way until it stops and then press WRITE.
5. Press the MEMORY up/down pedals to set the sensitivity of the toe-end switch (1-9). Lower values will require less pressure to activate the switch.
6. Press WRITE to save the settings.