On a resent flight the manifold pressure gauge stopped working, the gauge display had a red cross through it. Upon inspection the ground wire was found to be broken, after the wire was rejoined and the unit turned on the same red cross was displayed, a check confirmed that power was getting to the transducer and that both the black wire and the green wire had continuity. Is the fault likely to be the transducer or in the unit itself. The unit is a AF3500 non S CPU