From the inside pic can't tell if its a dual
transducer.
Look for an Airmar part number on it. Most transducers are made by
Airmar.
Usually the
transducer goes bad, but also it may be the
head. Depending on the age of the unit, its a crap shoot on
buying a new transducer than just replacing it w/a new df.
Did you look for another tranducer? Looked at the
current NASA page and the newer "spare" transducer w/the perpendicular pin (now plastic) was for speed. They also had a separate depth transducer.
Bill O.