fishmanoz yes polarity is the same on inner and outer tracks also power clips are wired black to black and white to white . have now disconected inner and outer tracks electrically just running outside track. easterner still running fine today no problems, second shunter coming back from hornby repairs tomorrow will see how that runs. other shunter ran fine for six days when that come back but then seized up ,still to contact hornby about that, hopefully they will repair it again for me. GM100m controller is only one month old , this session with the trains is the first time using it and still one shunter has broken down. many thanks for everbodys help , have to put set away at the weekend probably till after xmas will let you no what happens