So I have a new to me 1993 Celeberity 190 BR with a Lowerance digital depth gauge on the dash. It is the 2" type just like the rest of the gauges, just with a "alarm clock" style number display and an up and down button. Not sure if this is standard factory equipment or if it was added some time after but it is not working correctly. Numbers are sporatic and also the glass is cracked. So this is my first boat with instrumentation like this, no clue how it works, and just want to get everything working properly. Assuming there is a sensor some where (transducer??) cant see anything under the boat. Where do I start?