Go ahead and take a shop light and hold it on one side or the other of the radiator and make sure you can see light thru the hole thing. Wouldn't hurt to wash it out anyways. Our MF 8560 would overheat after running for about a hour and we thought the radiator was clean, then spent about three hours with a garden hose washing it out and end of problem. After checking radiator is clean and still overheats personally I would check thermostat next, might not be opening all the way.