Diagnosing depth gauge problem

My depth gauge worked perfectly for 2 years always reading the correct depth while running up to 40mph. It recently started working intermitently and just blinking the last read value until it gets another good reading.

I'm trying to figure out if it's the transducer or the gauge that is bad, or perhaps some other problem I'm unaware of. Is there a problem more "typical" than others that causes this?

I've checked that the transducer is still epoxied solid to the hull and it looks solid (and hard to replace).

Thanks for any help.