Hi stgraves,
You will find the transducer in the same compartment as the shower sump. It is located under the removable flooring panel in the v-berth. You can check it by removing the transducer from the cup. if it is an older P-79, which I believe yours is, it can be removed by twisting it 1/4 turn. Check to make sure the cup is filled to the top. You should see pink fluid inside the cup. This is an R/V type antifreeze, and anything similar will do. Then just make sure the transducer is seated properly by placing it back on the cup and turned 1/4 of a turn. Orientation is important, but that is easy to tell by simply making sure the top of the transducer is relatively flat with the water line. If it is not, it is simply off 180degrees. Just remove the transducer, turn it 180 degrees and reinstall.
Thanks!
Ralf