I recall when I was a kid, one of my uncles had a Snapper walk behind mower with a similar friction disc drive. He was amazed when I tightened the drive tension spring on it.... I did it out of necessity because it was too heavy to push if the drive was constantly slipping. He never did understand anything mechanical. LOL
My series 6 Snapper has not been run so far this year, but I need to. Machines that set too much can be as bad or worse than machines that are abused. I got this thing from an elderly friend who has now passed away, but he loved talking about it. I think the only reason it got parked was due to a stripped blade bar. I have since reconditioned most of the machine and worked a lot of the kinks out of it.
I might get energetic and even paint it someday soon. These machines were built simple and built to last.