On some occasions, performing a hard reset can solve issues with the ISA units.

To perform a reset follow these steps.

1. Hold down the 'Clock Select' & 'Ext Sync' black buttons on the right side of the ISA unit. For an ISA Two, hold down the 'Z In' and 'Input' buttons on the very left of the unit.
2. Power off the unit using the power switch.
3. Still holding the buttons, power the unit back on using the power switch.