L 3901 has been down for a couple months. I just haven’t had time to get to it. It was last used mowing and started struggling while driving it. Made it to a safe enough spot to park it. Since then, it will not attempt to crank. Dashboard comes on, glow plug buzzes, but when turning the key, I get a single click. Nothing more. Have wiggle tested all of the normal safety switches, but have not yet taken anything apart or done any multimeter testing. Suggestions on most likely culprit? Thanks.