Check the reader laser for a buildup of dust. Do you have a cleaning disk? Its a disk that has a brush built into it that spins briefly cleaing laser lens. This is the best approach and saves dismantling you xbox. Otherwise you will need to remove top panel and locate the laser lens, usually tiny blue glass, and carefully clean it with a cotton bud and isopropyl alcohol or metholated spirit. Good luck.

Disconnect power at outlet. Backflush drain hose with house pressure. Check washtub for water flow while back flushing. Stop back flush. Check washtub for small foreign objects, or fur balls etc. reconnect drain hose to house drain. Turn on Machine and run pump and spin cycle.