Plane has been flying for 10 years. No problems. Last flight, I noticed the Amps was 0. Voltage rock steady. So I replaced my voltage regulator. Went flying, and Amps still show 0. Then I ran wires directly from the shunt on the firewall to the pin connector on the D120. Ground run, and still amps showing 0. Voltage is always rock steady, so I believe the alternator is charging, just not getting an indication of amperage on the D120. What else can I check?