Purchased an SM-8 amp in need of repair. Where does the ground wire go? See pic. Is the voltage selector correct or should it be 120V? Where can I find the screw in fuse holder? A replacement? The amplifier states that an 8 amp fuse is needed. The fuse and holder I am using are from the preamp. With this fuse in place I am only getting 30 ACV to the fuse holder, tested inside the amp wiith DMM. Ideas?