I just bought my first stick welder to learn on. The welder is a Mid States model and has a "Missing Link" Box on top. anyone know how this works. I attached a few pics. I thought the leads from the upper box plugged into the lower unit on desired amp output and the welding cables plugged into the upper box. I am not sure why both boxes have on/off switches and why the upper would be on or off in some cases. Any help would be appreciated. Well I tried to ad pics but doesn't seem to work