Hello I have been using a Lincoln Precision 185 TIG /Stick welder , the unit seems to work fairly good except for the Amperage Control , as one goes Upor Down with the Control Dial the digital Amp. readout bounces all over the place ,once I settle on the correct Amperage , the thing stays pretty stable , I haven't had the welder apart yet but am suspicious of the counting or pulsing mechanism that is hooked to the Amp. dial , from my HAM radio experience they usually use a Opto Interrupter or Hall effect counter , could also be using a mechanical contactor , wonder if anybody has had this phenomena and if so what did you find was the problem ? , I don't have a Service Manual , only the owners manual . Thanks' Phil L.