I've not been able to find any new solutions so I thought I would try repeating everything I've tried again. I started by re-cleaning the connector as, logically my error only occurs when not plugged in to anything. To my amazement the problem is now resolved, I did take quite a while cleaning this time using toothpicks, cotton buds and nail varnish remover. So I geuss I should have cleaned it better in the first place! Doh! Anyway it's FIXED!!