Spare wheel pulley won't wind down fully

[Ceist Beag]

Sorry I don't know the technical detail on this but hoping some of ye have come across this before. I have a Ford Galaxy (03) and when I had a puncture I put on the spare wheel but left the old tyre in the back rather than put it into the spare wheel well. The spare wheel was kept attached to the underside of the car via a type of pulley wire and block which winds up tight to the underside of the car. Now when I try and put the spare wheel back underneath (having got the puncture repaired) I can't get the wire and block to wind down to the ground - it only winds down about 6 inches and then starts winding back up again.
I spoke to a mechanic who suggested the wire may be wrapped up inside and that I need to get it replaced but a replacement would cost €80 so I just want to check out if anyone has come across this before and found a solution before I fork out for the replacement.

 

[aircobra19]

Maybe you can dismantle it and have a go at fixing it. What have you got to lose, if the only alternative is you'll be replacing it anyway. The new one might do it aswell in the future.