Andy,

Get the van up at all 4 corners, 8-10 inches is all the lift that you need.
Remove the spare tire and its tray.  Climb under the van and lubricate every
part of the shifting mechanism which you see that slides, rotates or rubs
against a gate.  If you want to be especially thorough, remove the shift
lever, take it apart and lubricate the ball joint.  If you do not want to
remove it, try to force some grease into the ball joint from above.  I use
white lithium grease since it is rated for use on plastic.  One thing, do not
loosen the u-joint in the center of the shifting rod unless you know how to
adjust it properly.

George