I have an intermediate problem--sometimes top works fine and others it does not. When I open the top, the back cover goes up and the roof goes into its section and folds up neatly--then it stops. The conver does not go back down. I then go to close the cover and it works fine except for the last step. When the rear window goes back to closed the windows should then go up and they do when working properly, the do not go up, however, when it is in failure mode. It appears as if a sensor in intermediately failing. Can someone tell me where such a sensor would be located so when it does fail in the open position I can test the sensor.