Somewhere between Anchorage and Tok this summer, I got totally fed up
with the three screaming kids and stopped the bus beside the road, went
out and threw the door open to yell at them (you just can't yell properly
while driving!).  The door came off.  Seems like I was a little too energetic
about opening it.  I stood, looking forlornly at my door, one corner in
the mud of Alaska, the rest hanging on by the rear slider hoping not to fall
into the mud (and over the cliff into that glacier below us) while my wife
gave me a earful.

The odd thing was that the door never worked well on this bus before this,
and after I got it all aback together, and we continued on our way, it has
worked perfectly!

Now this might not work for you (after all the old Vans have a different door
mechanism) but it did for me!

So pile your kids in and drive for a couple of weeks straight.  Pull off the
road and *really* whang the door open (the road I used was right purty -- I'd
recommend it!) and lubricate it to your hearts content!  Be sure your 
significant other is there on hand, and you'll need a couple of wrenches.
Maybe the mud helps, too.

malcolm