I don't have a 210EXT but a 255EXT and it should be the same on T4 you only get to use the Amptrol up to what ever setting on amps you set on the machine. I set mine to max. then I have the complete range of amps. When you first start by pushing the start button once it will start the arc, then you can use the Amptrol up or down then push the start button again and it shuts off. Mine has to be in pedal and T4 at the same time to work both light are on. Like they say if all fails read the manual.
Everlast PowerTig 325EXT (Canada)
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Millermatic 252 plus 30A Spoolgun(Canada)