Put a shim (1/8 to 1/4") under the spring of the rear idler suspension. I noticed that depressing the idler suspension increases the track tension ever so slightly so I did this "fix" and now I have driven for several hours without one thrown track. This compares to throwing a track about every ten minutes before the fix. I have driven in grass, on gravel, concrete and pavement as well as plain old dirt - even wood chips, without any problems. This "adjustment" has made driving the Stuart much more fun! Hope it helps!