Air cooled or water cooled?
Try cleaning it once it is completely cool (like overnight).
A high pressure cleaner will probably work well. If water cooled, it is easy to find that the radiator is dirty, and might be covered with oil or something. Air cooled can also be coated with some oil mist too, and this collects dust that will insulate the metal from the heat.
3000 hours is a long time, and even some small amount of oil mist would collect a lot of baked on dirt and insulate the cooling fins from the air going over it to cool the generator.
Also check to see if you might have picked up a plastic bag, or other trash on the air intake to the generator. .
Fred.
