I have been informed that some fluids used for coolants will contribute to internal parts getting eaten up also. I have used 30+ year old machines and I have used brand new machines while teaching and at work. I have used water, ethylene glycol, and Miller coolant. Most of the setups dont seem to care on the specifics. My personal Syncrowave quit cooperating shortly after I got it and ate up a torch power cable. The only change was to flush and replace the torch and fill with Miller coolant. Haven't had a problem in ten years or so.
Two things. HF is weird stuff and grounding of equipment, workplaces, and the work itself is often overlooked. Most of the time, it is not an issue. Some times it causes all kinds of weird stuff. I have seen strange stuff happen around a TIG work area. I know two places where every GFCI oulet has been messed up and I have seen thermostat controlled heaters try to start with each arc start. I worked at a place that had to build a seperate building for the offices and run a dedicated power service to it because every piece of electronic office equipment was damaged by HF when everything was in the same building and powered off the same line.
I do not understand all of it. I have done a fair amount of electrical work but I am nowhere near a pro. I know I have seen the importance of a perfectly grounded and controlled setup and I have always been instructed as such when working directly with Miller and other reps within the industry and at school.