I just bought a new 798ci and a new 598ci the 598 is mounted on trolling motor and seems to be working fine, except no 83 HZ display in simulation mode. The 798ci is mounted on console. It also has nothing in simulation with 83 HZ. and does not work in 200/83 HZ. It seems to be okay in 200HZ. Also on shutdown down when you hold power button in it says shutting down in 2 seconds but takes much longer and sometimes looks up. I swap locations with them and get same results, so I know it is nota transducer issue. Any thoughts on this?