A 10 year old RV is VERY likely to need new calipers especially if has spent a lot of time sitting between outings and the brake fluid hasn't been flushed at least every 5 years. That's the interval I have gotten in the habit of using. Since I started that maintenance regimen, I have yet to need a replacement caliper on ANY of my vehicles. After 5 years the fluid will come out slightly darker than the new fluid. Flushing something that has gone longer than that will produce fluid that looks like root beer.