Here are some pics showing the cable system and mechanism when the roof is open and closed. I've also shown the heavy duty wheels and track.
this is the rain detector I use, but it seems to have trouble if the rain is very fine.
http://www.youtube.com/watch?v=ZQv5sAe6RfQ
http://www.ebay.co.uk/itm/RAIN-SENSO...item2a2e65f371
let me know your thoughts