Ok,

Thank you all for the help, I am using a Futaba 7UAPS (PCM 1024).
Well, I am guessing that the reversing Y lead is the problem, so whats my next step - I have used all the channels in my RX, so by the sound of it my best option is to use a standard Y lead and reverse one of the servos internally - how hard is this to do? And how is it done?

RJ