Help, my supermig 150 keeps blowing it's fuse when I pull the trigger. It started after I had to turn it up to its max to weld a quick job, following day attempted to weld a small patch on my landrover, it switches on (fan comes on) and after holding the trigger for a couple of seconds it blew the fuse. I've been through more fuses than I care to think about trying to find the problem. I've disconnected the motor, check the wiring and checked the pcb for any obvious damage and it still blows the fuse. Any ideas on what the problem is?