I always thought there was a bad solder connection that caused my FM to cut out intermittently, but it turns out this was a very simple repair. Remove the radio and unplug the connections (make sure you know the security code). Take some emery cloth and lightly clean the end of the antenna cable. Now look at the antenna port on the back of the unit. You need to bend the part inside that contacts the center conductor of the antenna cable, NOT the OD of the antenna cable. It is inside the radio, but I was able to use a small screwdriver thru the ventilation holes, and apply a bending moment to the part that contacts this conductor. This part acts like a spring to make contact but it loses its resilience over time, loosens up, and then your FM starts to cut out. Ambient temperature changes seemed to make a difference on when it would happen. Be careful, you are just trying to make better contact between this part and the antenna center conductor, not break the circuit board. Just a apply a little pressure to bend this round hollow part closer to it's center axis. You'll see the part inside is manufactured with rolled metal with a split facing up. Apply pressure on each side of the split individually, as close to the split as possible for maximum effectiveness. Bending the far side can be done using your tool thru one of the holes at an extreme angle. You could remove the bottom cover of the radio and provide support with your finger at the area where the antenna lead-in is soldered to the circuit board while you accomplish this. This repair may apply to more models than this SC-815 radio. I also noticed better overall FM reception and all the electrical interference noise on the AM band disappeared.