Hello all. I have a customer that called said his generator is kicking on during power outage all breakers are on but no power being put out from generator. He checked line side of breaker at generator there’s not any power being produced from generator. He also stated that there are solid copper wire pieces laying in the bottom of the generator cabinet. He also said it appears that there’s pieces of paper towels in the bottom of generator housing like it was sucked in through the motor apparently left inside when he changed the oil. Any thoughts could it be rotor or stator or both could the paper towels have caused this. 
A roll of paper towels left inside the system once destroyed a steam turbine at a nuclear power plant.
It did several million $ of damage, so they can be quite destructive.

That said, if they clogged the cooling airflow they could've caused severe overheating, warping the rotor/stator and causing damage like that.
Copper in the bottom of the housing indicates that the stator and rotor are trashed, it will not produce voltage, it can be repaired but may be time for a new machine.