ok so the bit below may be really confusing and really needs pictures to explain. if you are not interested in the intricate workings of a window regulator please look away now!!! This is the most boring thing youll read all year.
if the system is anything like the system on my old mitsi gto which i think it might be.
a wire is attachced at one end to the window, it goes along the length of the regulator and round a plastic wheel and into some covering which for the life of me i cant remember its name (steel wrapped in plastic to keep tension). the cable then passes through some springs to keep tension on the system and into the motor housing. in here it spirals round a reel a number of times, (perhaps 5) to aid in gripping the cable and provide the reeling in/out action . at the centre of the reel this length of cable ends with a block hooked into the plastic of the reel. another cable starts, again hooked by a metal block and continues round the reel before exiting the housing and going through another spring, down the sheathing, round the other pulley and then attached to the window.
the purose of having 2 cables is to give fixing ends to attach them to the reel preventing slippage. basically when the window is all the way up, the point where the cables cross over and enter the reel is at the top, and as you wind it down they travel to the bottom. the amount of cable wound round the reel is equal to the distance the window travels.
the motor uses a worm and worm gear attached to the face of the reel to turn it. this worm gear arrangement is what prevents you from pushing the window down yourself.
if the cable is reeled out to far it will be damaged. also the reels grooves the cable sits in wear over time and so the cable falls out the groove and winds itself up in a ball and ruins the regulator.