Transducer problem?

I have an 8 year old B60 thru hull transducer that was connected to an a67 and worked flawlessly for years. When my a67 was damaged, I installed an a77. My research with Raymarine indicated a B60 was an authorized transducer for an a77, so I did not replace the 'ducer. The machine works fine on dead calm, flat water but the first wave or boat wake I hit, I get a message saying transducer not connected. The depth function will not return unless I power off the MFD and start it up again. I had my installer re-check all wiring connections and even put heat shrink around the connections to ensure they are snug and stay that way. No help.
I am sure you have heard it all......what is the cause of this issue?

Thanks.