If the EXP 1 switch indicator on the BOSS GX-100 does not light up when the expression pedal is pressed, recalibrating the pedal may resolve the issue. Recalibration is also recommended in the following cases.
- The volume cannot be set to zero using the volume pedal.
- The PEDAL FX switch does not respond correctly.
- The pedal feels out of adjustment after extended use.
Refer to "Adjusting the expression pedal (pedal calibration)" in the GX-100 Reference Manual for the calibration procedure.