Turn off the power for the microwave by either unplugging it or turning the power off at the breaker box. Remove the grill from the top of the microwave by pulling it off.
Remove the screw from the control panel with a Phillips screwdriver. Pull the control panel out of the GE microwave and label each of the wires using a marker and tape. Unplug the wires from the control panel by pulling them off.
Locate the old fuse in the compartment where the control panel mounts. Pull the fuse out and place the new one in the microwave. Connect the wires onto the control panel and install it in the microwave.
Tighten the control panel retaining screw with the Phillips screwdriver. Install the grill on the front of the appliance and push it until it snaps into place. Restore the power to the microwave and program the clock.