Mark,

that was it... thanks to a friend of mine who helped me with his
oscilloscopen we could easily fix the issue and now the tuner is back to
life.
Thank you so much !

Franco.

The discriminator adjustment is off. This is actually a very common
problem for digital tuners. There are two discriminator adjutments in a
typical tuner. One adjusts the station centering (I suppose you could call
it a "zero-cross" point), the other affects the distortion more. For this
reason this alignment should be done in a shop by a qualified tech. In
rare cases an out-of-spec 7.2 mHz crystal could cause the same symptom.

Mark Z.