The issue with your 48" slow rise roller shade is likely due to a worn or lost tension spring, which is common over time. First, try re-tensioning the shade by fully lowering it, removing it from the brackets, manually rolling it up, then remounting it. If that doesn't restore function, replacing the internal spring is recommended. The most common replacement spring size for your shade is the 3/4" (0.75") version, which fits most OEM slow-rise RV roller shades. You can order this replacement spring directly to fix the problem. However, if the fabric or other components are damaged, consider replacing the entire roller shade with a premium blackout slow-rise model available in custom sizes and colors. Always verify the spring diameter before ordering to ensure compatibility.