Sounds to me like its the transducer. And may also need to send the unit in for the up dates. I had the same problems your discribing. And replacing the transducer and the updates did the tricks. I think it will be around $ 200.00. To get it working right again.

My brother and a freind have both had this same problem.Angle of transducer was fine in both units and the problem turned out to be the tranducer both times.Both units were also in the same 5-6 year old range.Note,I also pick up the thermocline,downriggers and bait pods on my low end unit(500 doller) polebreaker