I've had this welder for a while now, don't use it much. Last use I was welding some mild steel 1/8" stock all was good. Went to use it again on some 16 guage exhaust piping the welder will not change current on the knobs, the data display reads -30. When I attempt to weld it gets a really weak ark not even enough to penetrate a tin can. I went through the manual it came with and the troubleshooting says to send it in for repair. Being that I needed the welder to finish my exhaust and get my car back on the road I took it to a welding repair shop here in germany. They opened the case and took one look at it and asked for a schematic. I told them I didn't have one and they basically said they wouldn't touch it. So now I need to get this thing repaired some how.