Fish Finder depth reading just blinks

[bosshoss]

Hello all, as the title says my depth reading just blinks 60 ft on my Elite 4 Dsi fish finder. Other than this issue seems like ff works fine.

I looked on the internet and found a couple of possibilities but have ruled them out already as the culprits.

Running a Elite 4 DSI ff with a thru hull transducer set up.

Anyone have any ideas ?

Thanks....