insert the one end through the fully opened glass window, let this end against the door wall inside of your car, pull back the other end while you lean against the car frame.
I fixed a gapped door between the door and the car frame several years ago.
But be careful, you don't need lots of force since the tube (as a level in physics) is long enough. Put something hard under the rod inside of your car and also sothing like towel or old clothes between the tube and door frame outside. You might need several tryial. Use lighter force first. Be careful, try not damage the door since inside of the door has a downed glass. Ask someone to help you if you have hard time to do yourself alone.
This is just a friendly suggestion. For me it worked. The work is a risk. Be careful, I am not responsable for the damage if you use too much force so that the door glass is damaged, the door is over bent or your waist is hurt.
Good luck.
