You might want to check the "backup valve" too. This is the ball-shaped thing about 5 feet from the cleaner in-line in the hose. This thing is supposed to cause the cleaner to reverse and relocate itself in the pool every 3 minutes or so.

There should be a fairly powerful stream of water coming out of this valve every 3 minutes, lasting about 35 seconds. Otherwise no water should be coming out of it. Mine got stuck in this position and as a result the cleaner and the backup were fighting each other. End result - little movement and a quiet tail (due to loss of pressure).

Worth a check.

~Rick~