B&D hedge trimmer GT370-GT371 intermittent electrical fault. How do I fix ?

There is an elctrical fault in the front handle, which was identified by a local garden tool servicing shop who couldn't repair it because they didn't have a B&D agency. This fault causes difficulty in starting/resuming cutting. B&D referred me to a parts supplier but offered no advice on what to replace or how to do it. B&Ds servicing agencies are not a practical option. I have the original leaflet supplied with the machine which has an exploded diagram of numbered parts. The machine was bought in October 2004 and has been used once a year(week at a time) It looks immaculate and works swell -- when it works