The tension sounds about like I run my T180. With a straight-edge along the top of the track, I like to run with about half an inch of sag. Obviously, too tight will wear the track/sprocket faster. Too loose and you know what happens. Really easy to add grease to increase the tension, and just open the bleeder nipple right next to the grease zerk to loosen it off. Catch the grease in a paper tower. Just one or two pumps on the grease gun will make a noticeable difference. Now, why did yours derail? Were you on a side slope? I'm disappointed with my tracked machine on side slopes. I installed off-road sissy gauges (tilt gauges) and drive by them most of the time. I now know that 15 degrees is fine IF IF IF the ground is smooth. If there are rocks or stumps, I think what happens is one of the rollers will ride up on it, allowing the rest of the track to hang down loose. With side pressure on it, the track tries to derail. I really messed one up when I was learning, and had it derailed about two inches. That time I was probably running the track a bit too loose, but the biggest problem was that I was running over 3 or 4" diameter logs on a 20 degree side slope. Took half an hour to finally get it back on, by just gritting my teeth and forcing the machine forward. What I could easily have done (if I knew enough back then) was to let a handful of grease out of the bleeder to get some slack, helped by put a small log between the track and the sprocket and move it forward enough to compress the tensioner grease chamber. With that much slack, I probably could have put it back on much easier. Then just pump up the grease chamber and we're back up and running.

---RC