Tom,
Yes, it is not a pretty job and could be very disappointing at best. In my case, the rear end of the bottom corner of my LR slide was flush when new. However, it became lower after about 6 months. Beaver Services Center in Wildwood adjusted it under warranty but again it came down after about 3 months. I took it back and they did a whole lot of adjustments inside and outside. Again the thing. lowered itself to that 1/2 inch lower in the rear as compared to the front. Well to make a very long story short. It has been in that lowered position for 11 years, 80,000miles, 5-6 months a year on the road with no problems and has never leaked water during 2 hurricanes and a tornado. There may be a simple answer to this problem, but so far nobody has shared that with me.
Good luck,
Karl