ST50 depth transducer

[CScape]

i have a older ST50 tridata on a 33 ft sailboat and the depth readings have suddenly become erratic. At the dock in the marina it reads 11 ft which is correct but not long after getting underway the reading begins to flash and will continue to do so over various depths. On a few occasions it has seemed to have woken up and started giving accurate readings? I have listened to the P19 transducer and it is ticking. Does this sound like a transducer or display problem? it is to be launched in about 2 weeks so I need to make some decisions asap.