I had this problem and if you are going to dismantle. Check the Starter Pulley cog for damage.
Have a look at:
www.shouldersofshoreham.co.uk
as they have a blown-up diagram of all the parts for this model.
GazJ
October 2008
take the casing off and wind the spring back its fiddly but it should be fine..
billy
October 2006
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