How can I fix the timer switch on a Dualit 4 slice Model 4SLGB?

Hi everyone, does anyone know how to fix the timer switch on a 4 slice dualit toaster? I think its a 2004 model as bought it second hand with the fault and dont really want to spend out on a new timer if I can mend the one i already have. Basically you turn the timer around to the 3 minute mark and it graduallys goes round then stops. Then you have to turn it a little bit forward to make it go again. This does not effect the toasting of the bread etc so if you forget about it, it burns! My husband says I shouldn't have bought it with a dodgy timer! But it was a bargain! haha