So about a month ago when I went to start my 641 it would just click once and then nothing. I put a charger on the battery and battery wouldn't hold. Purchased new battery. Charged and went to start ... again just a click. I assumed it was the starter solenoid and put a new one in. Now when I turn the key to the on position the starter continues to turn without me pressing the starter button near the shifter. The tractor starts but I never hit the starter button... It's like a modern car.... any ideas? it use to be when I turned the key nothing would happen until I hit the starter button... It's a 6v system FYI. Any help appreciated!!