I have sent Sara from Wren an email about the problem so I'll post the answer when I recieve it.

It's 6 AM & time to get ready for test flying! [X(]

Like I said the engine runs perfectly anyway so I'll sort it when I get back.

If the engine stops in flight I cannot see any problems, I always come home with a model & have never had one stuck up in the sky so far. - John.