Broken cap for depth sounder sensor

[chas5131]

Have a 1969 Ensign.
There was a depth sounder sensor mounted horizontally in the bilge when I got it.
The cap for the sensor has cracked and must be replaced.
Signet website shows no such part.

Suggestions?

Just had the Ensign restored. When they put it back in the water it started sinking because the cap had cracked.
My ship finally came in. Had to write a fat check for it and now it wants to sink.

[mitiempo]

A picture would help give us a clearer idea.