Hi again all.
To put matters right for anyone reading this thread, I titled it with Forge Electronics Rudder Mixer as I originally thought that was where the problem lay. I now know that the rudder mixer was NOT, repeat NOT, at fault at all and is working perfectly. If you have the room I would recommend that you give one of these units a try. It is fairly easy to set up and has lots of options as to how you want to set it up to suit you. And no, I am not getting anything for saying this! I just don't want anyone thinking the units are iffy because of what I originally said.
Thanks for your help with this,
Take care, don't be an idiot, stay safe.