I have a formaula SR311. The gauge stopped showing me when the drive is trimmed all the way down only up but the drive operates fine. Is this a trim sensor problem? I wasn't sure cause it shows it one way but not the other.

More than likely needs a sender. Those things seem to mess up all the time. About all you can do is put a new one on and hope it last a few years.

Don't you have Mechanical indicators?