If you've ever had your window hit the bottom of the door with a clunk
on your pre-electric-windowed vanagon, and have taken the thing apart
and found that the entire operation comes down to tiny plastic ridges
that keep the slider affixed to the guiderail, and you didn't want to
pay $80 for a new mechanism, read on.

That cross-piece (the slider, the one that the window glass bolts to)
can be levered up away from the slide (save the two plastic guides, and
if you don't see them, get a flashlight and look inside the door panel
for them) so that it can then be moved transversely to escape the tiny
plastic ridges should they still exist.

Whether they do or don't, if even one is missing it will allow the
nylon fixture to pop off the metal frame that lifts it up and down,
allowing your window to fall. But if you examine it closely, you'll see
that the round metal button in the center of the lifting assembly
(obvious if you have this thing in your hand) has a lip around the top.
If you make a metal (I used aluminum) clip about an inch square with a
hole the size of the SMALLER diameter of the metal button, and then cut
the metal from the outer edge to the hole so you can spring it over the
lip of the button and tap it flat and secured by the lip, your window
will stay connected to the rail.

The size of the hole must be exact. I cut a slot in a cardboard temple
until it would just slide under the lip with no interference, used a
small compass to figure the exact radius from that, and transferred
that to the metal. I drilled 3/8" (it's closer to 1/2) and dremeled the
rest.

Unfortunately, my digital camera was sent back to Canon for repairs, so
I don't have pictures. But I would be glad to send a drawing to anyone
who needs one.

Jim