Sweetjeep, don't know if this will help but I had a problem on my 06 3720 that suddenly, without warning wouldn't crank. I got a click when trying to start and the headlights worked. Jumping with my truck battery didn't work. It would try to turn over once, and that was it. Long story short, it was a shorted cell in the battery. Dealer replaced battery and it lasted about a year. Same problem, a shorted cell. This time I got a JD Strongbox battery, and it has lasted about 3 years.
good luck, Dave
Thanks Dave. The tractor is running. My darling little boy pulled the PTO switch. It never even crossed my mind to check it as I have the backhoe on and there would be no need to pull it. However, when you are a 3 year old and there is a yellow knob to be pulled when you are unsupervised.
I should have known when I got on and everything was out of whack..