TL12v2 Overheating Issue

[Boston3220]

I have a TL12v2 that's three years old with 350 hours on it and is used strictly for ranch use. The engine overheats whenever I'm running the brush cutter after about 15-20 minutes. The warmer the weather the quicker it overheats. I have to shut down the brush cutter and wait about 5 minutes for the overheat buzzer to stop and cool down enough to start shredding again for about 5 minutes before the engine coolant temp goes into the red and the buzzer and red warning light come on again. The hydraulic oil temp never goes above the bottom green peg. I pressure wash the radiator fins on a regular basis but it still overheats when using the brush cutter. The radiator is full of coolant and the brush cutter is turning in the correct counter clockwise direction. The dealer has no clue what the problem is. Could the radiator possibly be plugged from the front (engine) side?

Any thoughts or suggestions?