Push down on the battery cover to open the battery compartment. Insert a 9V battery into the battery compartment according to the correct polarity as shown in Figure 14. Then push up on the battery cover to close the battery compartment. 3. The LED indicator will flash briefly when power is turned on to indicate normal battery status. If no flash occurs it has either no battery, the battery is drained or installed incorrectly. Change accordingly. 4. 4-Pin Jack: Volume can be adjusted by the gain control. Gain control has no effect when the switch is in the �GT� position (Guitar). 4-Pin Jack: Align and insert the 4-pin plug into the jack accordingly and tighten it in the clockwise direction as shown in Figure 15.