...well maybe... Often times, however, it is simply the retaining clip that holds the rod has fallen of and needs replacement. This involves removing the door panel for investigation. You may wish to invest in a clip tool (cheap) if you remove the door panel so you do not damage the panel.
...I would infer it might be rheostat...I still give my previous advice....check ground first...rheostat second. The gator clip that yhou have to slip on the end of your meter's probe....along with the probe wire works great for a temporary ground wire to make sure its good. =-)
well not sure how to interpret this one... BUT the path of heat is pretty self explanitory. follow the path and remove any impediments. =-))))
...PB Blaster available at your local auto parts store...one of the best penetrating liquids available. Use it liberallly on the tracks.
...Gareth