Just for information,
Domenico
IU4FCW, a friend of mine, checked the transducer and found anomalies in the three transistors
Q1,
Q2 and
Q3.
He replaced all the transistors, even if two of them seemed to be working fine and the transducer started working again.
The previous check on the three diodes had given positive results. After replacing the transistors, the next step would have been to replace the two
LMC6482s but it wasn't been necessary.
Maybe this can help someone else
Best 73'
Enzo, iw7dmh