If you haven't removed the wheelboxes, you might consider doing that now. (In for a penny, in for a pound). The grease in there is almost 50 yrs old and if the boxes get sticky, it makes it difficult for the motor to overcome. I did this last year and remember the whole job was a bear but seem to have blocked out the unpleasant memories. You'll need to thread the cable through the wiring from the driver's side of the car and attach the passenger side wheelbox once you've threaded it through. Be careful you don't dislodge any wiring as you wiggle it through.