I have a Power Arc 300. I had to replace it with a new one because the job electrician wired my old one to high voltage and blew it up. Up to that point this machine had been bulletproof. I was very happy with it. My new replacement PA 300 which I've only used a few times has a small issue. While welding, the amperage seem to increase on its own. I noticed the dial turns much easier than the last one and is hard to adjust. very touchy. I think the inherent vibration of the machine might be causing the amperage creep. Is there a way to adjust the dial tension?

Also, do you think my old machine is worth fixing, or is it not cost effective?

Thank you, Mike