What I do, for what it's worth, is spin the cable tension barrel all the way in so that the cable is slack, then back it out until the der works properly again. It's helpful if you have a work stand or some other way of running through the gears that will allow you to turn the barrel adjuster. Once you've got it working right on the stand, take it out for a spin and tweak it some more. I've found that an adjustment on the stand will need fine tuning on the road to accommodate actual battlefield conditions. As you found, things can get out of hand in a hurry if you play around with the limit screws without knowing what you're doing. Messing with the rear der screws can even be dangerous.