Just ran my 33' Grady offshore for the first time this season and ran great except that the yamaha gauge which shows speed and trip just displayed dashes with no info. Other 3 gauges read well. I have twin 250 four strikes 2005. Any ideas where to start trouble shooting? I have 2 hull mounted transducers for 2 Navnet2's and I get good readings on them and my RD30. Thanks