Watt-meter showing half wattage

Output power from the generator is showing half of the actual wattage. I checked the terminals and found out that two current wires are going from the main breaker to the switchboard, c1, and c3. Using clamp meter, c3 is showing 0.80 amps while c1 is showing 0. I changed the terminal of c1 but no change in the amps. I also found leaked oil at this c1 terminal. I cleaned the oil and use conductor cleaner to clean the terminal but no change.
It is a European style generator with output voltage 440V. One digital meter is showing 40kWatt but the analog meter is showing half power. The output voltage is correct 440V but the current is not right. The ammeter transfer switch shows zero current at line 1. line 2 and line 3 are OK.
I also checked connectivity with a multimeter and it beeps which means the circuit is connected. I have been trying on this problem for many days but could not troubleshoot the real problem. Can anyone help me where the issue could be? I will really appreciate your help.