I got my hands on a free Lincoln Idealarc 300/300 tig welder (ancient), but there is a problem with it. The previous owner claimed there is something wrong w/ the PCB because the foot pedal does not work in a linear fashion when pressed. Instead it acts more like a on/off switch. I have not been able to source a foot pedal to determine whether it is a problem w/ the pedal or the electronics. Does anyone know where I find a foot pedal?

Here is a pic of what it looks like (not mine):

Lincoln Idealarc 300/300

Thanks.