Equipment maintenance is so important and so is having replacement parts on hand. You never know when something is going to fail. There is a good chance that someone in this franchise will have a switch fail tomorrow. Will they be 30 miles from home with a full schedule? Everyone needs to have repair parts and tools in their van. My port-a-vac’s cord was beginning to look ugly and old so I ordered a new cord about a year ago and never replaced it. Well yesterday it quit because the strain relief broke 6 months ago, allowing a wire to eventually break. To my disadvantage, preventitive maintenance was ignored. When I got home, I put the new cord on but I also had in stock, a new strain relief and a new switch. While I had it apart, I replaced the switch even though it was still working(preventitve maintanence) My point is: Always assume that all of your equipment can fail at any givin moment and you need to be prepared. But furthermore, if you see something showing some wear, replace it before it totally breaks.