I have a PP 256 that I bought in 2012 or 2013. I haven't used it in a while, and when I went to TIG some steel DCEN, all I got was a very weak arc, not enough to melt even a razor blade, though I had 150A selected. I switched electrode holders and ground clamp to + and selected ARC, and got nothing. I checked voltage at the electrode connectors on the front and got no voltage.

Any ideas where to start looking?