Not sure what you mean by "guide tubes." The cable guides are small plastic parts that can be seen easily when the sunroof is open. You might need to push the roof with your hand to open it up all the way.
There is a good picture of the cable coming out of the cable guides on this thread. Mine looked exactly like this when it got stuck.
http://www.peachparts.com/shopforum/showthread.php?t=96149