Hi I have a murex tradesmig 165 and seem to have problems adjusting the wire feed the switch knob seems abit ify it wont turn down slow enough for welding cars does any1 know if you can replace the switch knob itself and where to get 1?
Might be something has gone a bit iffy on the circuit board. Normally the wire speed knob is in parallel with a couple of resistors and a trim pot. The trim pot will be a small square thing with a plastic screw head that you can turn with a small screwdriver.
Could be worth turning the main knob to zero and adjusting the trim pot until the wire just creeps out. With luck that'll give you adjustment for thin metal while still allowing you to weld thick stuff. If it doesn't there's something broken on the circuit board.
It`s cheaper to get the circuit board repaired. It is fairly common fault the board failing giving you no wire speed control. PM me if you would like info on where you can get them repaired.
could also be dirt in the wire feed control potentiometer (the bit you turn) which can give a very erratic control you can get a spray cleaning / lubricating fluid or just replace the pot. but dont use wd40 or anything not specifically for that purpose as it can make things worse due to being conductive