Non active depth transducer

[Rol1964]

I have an old depth transducer installation under the Vberth which likely hasn’t functioned in many years. (1974 Pearson 26…bare bones starter boat). All the wiring appears to be intact. The face of the instrument in the cockpit has deteriorated to junk.
Is there a way to test it to see if it might work? Can it be tested with a multimeter? Last question, should these thruhulls be replaced as a precaution due to integrity / life expectancy of the plastic below the waterline? Thanks.

[motion30]

A picture of your existing unit may allow it to be more easily identified