Sounds to me like you may have a bad switch. If you have power going to the switch, and nothing comming out then the switch is bad. I have seen "new" bad switches before. If you do have power on both sides of the switch when it is engaged I would look towards maybe the clutch failing and requiring more power to engage properly. You may have a bearing gone bad or something in the clutch. The jump box puts out far more amps then your battery or stator so that would explain why it worked that way. Try testing the load on the battery with a voltage meter while the machine is running. Set the switch to AC volts and touch the terminals to the battery. I think it should read somewhere around 33 volts A/C. Then engage the clutch and see what happens. It shouldn't drop more then a few volts if it does your clutch may need replaced. You can also do this test without the engine running but the volts will read lower and I'm not sure what those numbers would be. I hope some of this helps, Good Luck !!