i have an old victor torch model 100, the acetaline knob is very hard to turn. ive taken it off and i can barely turn the hex part from the knob. if i don't tighten it to the handle very tight, when i turn the knob it unscrews it from the handle. i would like to get a new knob, but am unsure where to get them. the welding shop is closed for the weekend, so ill have to wait till monday to see if they have anything available.