Originally Posted by Dead pirate
I think there is a one in thousand chance it's the governor. There is oil in the air tank tho. Not much but it's there
If your not building air pressure and there are no air leaks it's likely the governor or compressor, hopefully the governor. Bendix has some good YouTube air brake videos for system operation and troubleshooting.
Its not unusual to have a little oil/water in the wet tank. This tank allows the air to cool and water vapor to condense before the air goes through the filter/dryer.