Where to find a starter spring for my McCulloch 7-40 chainsaw?

In the starter pull-cord mechanism of my McCulloch mac 7-40 chain-saw there are two springs, a large clock spring and a secondary, strong spring housed within the nylon starter cog. This spring has wound in on itself and I need to replace it with a new one. Does any one know where I can get one from, or my nearest dealer so I can get the chainsaw repaired? I live near the Leicestershire/Staffordshire border.