If you download our latest software, it includes a program called Dusk, under the guiding section there is the ability to pulse the ST4 port connections manually for longer than normal periods. This would give you the opportunity to either test with a multimeter or watch the motor drive on the mount. If there isn't any movement clean the contacts of the ST4 port using electrical cleaner as this is the most common cause of failure.
Sorry to hear that you are having with your 314e. Have you tried this camera on a windows operating system to confirm that the guide port is switching OK? Have you used this connection in the past?