Thanks Chris
ive emailed John, however ive dicovered the problem the jack socket got a bit loose which I though t was the original problem. Ive tightened it up but it appears the black lead from the battery to the jack socket has come off, hence no power when the jack is inserted.
ive just got to get someone to solder it back on for me as I dont have a soldering iron and dont trust myself to do it anyway, the local tech will probably charge me £50 for 2 mins work
Mystery solved