I have the PP 256. When I'm cutting, it will all of the sudden greatly increase the plasma arc and cut much better. It will go like that for a second and then go back to the lower arc for another 10 seconds. I have verified all of the settings and connections. I am running 60psi pressure through the regulator and have tried increasing and decreasing pressure with no change in operation. The TIG torch operates smoothly with no change in output current.