Cub Cadet Series 7000 Tractor not starting

[MLhite]

I have a Cub Cadet compact tractor with a 30hp Mitsubishi diesel engine that will not start unless I connect my 200A engine starting battery charger, then it starts without hesitation. I have tried two different new batteries with over 500 CCA but when I turn the key to start, nothing happens, except the glow-plug light illuminates indicating a complete circuit. No clicking, like a car engine does with a low battery, just nothing. And yet as soon as I hook up the 200A engine starter, it fires right up. Make me think the starting circuit "jumps a gap" with the engine starter 200A, but not with the battery alone.
Any suggestions what I should change? Starter, starter solenoid?

 

[ILENGINE]

May want to check the ground connector where the negative wire connects to the frame. Remove and clean and reinstall. My next thought is faulty battery failing under load. Make want to ask for assistance and try putting a volt meter across the battery terminals and and see if the voltage drops a considerable amount when trying to crank.

 

[MLhite]

May want to check the ground connector where the negative wire connects to the frame. Remove and clean and reinstall. My next thought is faulty battery failing under load. Make want to ask for assistance and try putting a volt meter across the battery terminals and and see if the voltage drops a considerable amount when trying to crank.

Thanks for your reply! Will check these out.