Gear similar rubbing surface damage

[Sofistioelevib]

Hi guys,
during gearbox inspection i found the damage as reported in the images below on a bevel gear.

The position is first gear mesh between high speed shaft and intermediate shaft.
The problem is on intermediate shaft only and the speed is aprox 900 RPM.
Previous vibration data reported high vibration on first gearmesh frequency (aprox 20 mm/s@1XGMF).
Do you have any idea of the source of the problem and eventually how to fix it?

Thanks

 

[SwinnyGG]

Looks to me like wavy wear, which would indicate that you have some uncontrolled vibration somewhere.