My millermatic 175 developed an interesting problem today, I am in the middle of a car trailer building project, and started welding some 1/8" thick WW11 aircraft landing mat pieces on to 4" channeling, the wire feed speed will not change, it is running fast (70-80-90) even with the speed control potentometer disconnected. Have I fried the curcit control card ? The machine still welds but unless the voltage is turned up to 9 or 10 there is just too much wire feeding to make a acceptable bead. Anybody have a issue like this ? How did you resolve it ? Thanks HemiAl