The wheel bolt trick works very well, can't remember where I saw it now. Did mine 2 years ago and it's still OK.
You basically hold then jam a wheel bolt on each hinge on the inside and shut the door agaisnt the bolt, jamming the bolt in the hinge. Give the door a bit of a shove then take the bolt out and see what effect you had.
Can't remember the order - I think it's bolt in bottom door goes up, bolt in top hinge door goes down..... don't hold me to this!
I wrapped some insulation tape round the spare wheel bolt to stop it scratching the paint in the hinge.
