Sounds like you had the machine running in the wrong direction.I used to have one of those general drain machine , What would happen it that if the head hit something hard, the cable would loop around your arms and twist hard. You had to be very fast to take your foot off the petal , but even them it would take a couple of revolution to stop with you all caught up in the cable. this happen a few time and then never again i got rid of it.
Ignorant inspector. There are stainless gas lines with hundreds of psi running through them in industrial settings that are also subject to vibration.I always thought stainless wasn't allowed for Nat. gas. One time a guy at work took home some stainless to hook up his Nat. gas and the inspector made him change it to black. But that was 30 years ago