I have a problem with my Lincoln 300/300 TIG welder described as such. When i am AC TIG welding my foot control does not respond in a quick action. I can usually "pump" the pedal and get the amp. results i need but on other times it works as it should. I have noted this is not as evident in DC- mode but for the most part in AC TIG. This welder has the old 5 pin K772 pedal and i know SSC Controls has one of these but i hate to order this and find the problem is still there. Every other function on the machine works as it should except this sluggish AC TIG issue. Any thought would be well received.