I'm having a heck of a time tig welding a new stainless exhaust sytem. My settings: 15 cfh,( varied between 10 and 20), 2T, pedal, high frequency start, 8 seconds post flow, 1 sec preflow. I've gone from 40 to 80 amps and everything in between. I'm using 1/16" thoriated red tungsten, 308l 1/16" filler rod. I've used #4 to #8 cups. I'm having burn through ( amps too high ?), poor penetration ( amps too low?), and it's a mess. This is a brand new machine. Any suggestions other than send the tig welder back?