If it's been turned in the direction that moves the cage outward and nothing seems to be happening, it may take you putting pressure on the shift lever (the large left one) to push it all the way to the actual limit. You do need tension in the cable. You might also do this by fixing the cable and then unscrewing the cable stop on the downtube a few clicks to increase the tension.
If it's been turned in the direction that moves the cage outward and nothing seems to be happening, it may take you putting pressure on the shift lever (the large left one) to push it all the way to the actual limit. You do need tension in the cable. You might also do this by fixing the cable and then unscrewing the cable stop on the downtube a few clicks to increase the tension.