as above, read haynes but still confused

my twizzly thing that selects the interior air vent positions (windscreen, feet, face etc) on my s2 jammed a while back, out of frustration i turned it as hard as poss, which with a click unjammed it, but there is lil pressure when turning it now, n it dont select the positions
its not the 'groove' in the actual twizzly thing (!?), a fault with the cable maybe? i dunno where to look, ie where the cables go to lol

cheeRS
dre