Help with Lincoln TIG Foot Pedal

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Hey, first off you guys have a great forum and this is my first post.  I have a Lincoln Square Wave TIG 255 and I am running into a problem.   I think the rheostat in my pedal is going out because my solenoid kicks on, I get good gas flow, and my arc will stop when I let off the pedal, but the arc stays at a very low intensity and will form an extremely small puddle (about 1/16") and will barely melt the filler rod.  I typically weld anywhere from 85-110 amps, and bringing the heat up any higher even while welding will do nothing to change the arc characteristics.   Does anyone know how to check a foot pedal for a bad rheostat?   Its a 5-pin connector and dont know how I could do an Ohm reading on it.   Thanks for your help, Heimz.
Reply:I suspect two of the pins will be the switch and should read open. Verify that these close when the pedal is depressed.  It might be faster to depress the pedal and hunt for the shorted pins.  That leaves the other three for the pot.Two of the three should have a constant resistance. these are connected to the outer two lugs on the pot.  The third pin should connect to center lug on the pot and the resistance should change with pedal position.You might as well pull the pedal apart and take a look.  One other thing to check first is have accidently left the power source amptrol in local and only have the contactor in remote.  I'm not familiar with your Lincoln but I suspect it's possible.DennisThermal Arc 185-TSWMillermatic Challenger 172VictorO/AAtlas Craftsman 12 by 24 LatheEsab PCM-875Wholesalem Tool Mill-Drill
Reply:I have been having trouble with my amptrol also.  I have the exact same welder as you.  I am hoping it is the amptrol.  Lincoln told me that pins a b c are hooked to tje var. resistor.  A-B  should be 10k  b-c  should be 0.  As it is moved the resistance changes the other way.  Let me know what you find out.ps.  I think I have sourced the sliding pot for the handamptrol that lincoln said did not existBert
Reply:Originally Posted by beckmanbI have been having trouble with my amptrol also.  I have the exact same welder as you.  I am hoping it is the amptrol.  Lincoln told me that pins a b c are hooked to tje var. resistor.  A-B  should be 10k  b-c  should be 0.  As it is moved the resistance changes the other way.  Let me know what you find out.ps.  I think I have sourced the sliding pot for the handamptrol that lincoln said did not existBert
Reply:My elecritician used the previous tips and found the amptrol to be working fine.   I now have to send my welder out to a repair shop to have them look at the internals.