After much testing, the treads I was using kept slipping off both sides. The right side more than the left, but still, it was becoming obvious that a complete redesign was necessary. No matter how I arranged the wheels, sprockets, and treads, however, I had the same problem. I probably would have needed tensioners and something to ensure that everything was perfectly aligned and level. In the end, I decided to scrap the tracked system.
I did some research into wheels that would provide good traction and work well in an all-wheel drive system, as I still wanted K-9 to be able to spin in place and make effective turns. That was when I discovered mecanum wheels. These wheels are simply bad-ass! With these in the proper configuration, a vehicle/robot can not only spin in place, it can effortlessly move in all eight compass directions! Yes, even slide to the left or right!
So I saved up and bought two left-sided and two right-sided mecanum wheels, hubs, and four new servos that matched the hubs. They work beautifully.