Is it quite slim, about 5 mm (from memory)? If so it's probably the handbrake return spring. A new spring costs about £2 from Vauxhall parts dept. It's an easy job, any DIY mechanic can do it in a few minutes. Might need a pair of pliers to get it on, no other tools required.  Dont pay Vauxhall to do it, they'll charge £50!!.
                 gibby
                
 July 2009