The RS/SS selects Signal Sounds when the switch is closed. So it sounds like either you have a short in the wiring or something is amiss with the actual RailSounds board. Have you tried swapping another board in? You can try any diesel of steam RailSounds 4 or 5 board to see if the wiring is suspect or it's the board. If the new board still only gets Signal Sounds, you have a wiring issue. If the new board does full RailSounds, the original board is probably bad.