Sticky sunroof can cause the motor to get hot and burn out, but before that happens the teleflex cable will probably get all bent out of shape and pop out of the cable tube, and then the roof will not close properly.

Taking the roof apart is not terribly difficult, getting it back together properly aligned is a different matter. I would try lubing the sliding rails (top and bottom) with the roof in the car, and see if that helps. The chrome strips covering the rails can be easily removed by unscrewing the phillips screws ONLY. (the non-phillips are height adjustment, at least on the W124)