If your RV shower door is not fully extending and stops short of the side rail, this often points to an issue with the internal spring mechanism or installation alignment. First, check for any obstructions in the track or cassette that might block the door from unrolling fully. Next, inspect the spring mechanism inside the door cassette; it may have lost tension or become unseated during installation, preventing full extension. Reinstall the door, ensuring the cassette and latch post are mounted correctly according to the installation guide. If the spring is damaged or faulty, consider replacing it with a universal replacement spring compatible with Irvine RV shower doors, available through Elkhart RV Parts. Following these steps should resolve the extension problem. If issues persist, providing photos can help with further diagnosis or warranty claims.