Welding a bandsaw blade

Has anyone ever used a blade welder like the one in the picture? I called Powermatic and they didn’t have a whole lot of information on how to use it. The one video I found shows the process on a much newer machine. So, it’s not the same process. So far I got sparks but that’s it. How long am I supposed to press the weld button for? And what am I supposed to do with the handle that says anneal on the left and clamp in the center? Please help!