[Opper77]

I just downloaded the owner's manual to see the unit itself....a couple other things to try

1) make sure the rheostat isn't grounding out to the chassis through dirt, dust etc

2) throw a multimeter set on ohms on the leads to the switch and rotate it. you should see a varying number as you turn it... if not, it may be grounded out somewhere inside

3) just double check the voltage range selector and make sure its firmly seated into a setting. weird things can happen when its JUST out and its arcing to 2 settings (had an old Hobart that had this problem chronically)


Hope all this helps