For years I have been plagued by the sliding coming partially unlocked when
driving on washboard type roads.  I tried all the suggested adjustment
remedies and eventually adjusted the striker pin (Bentley pic 58-231) so
that the door would stay closed on the roughest of roads but there was a
slight gap at the bottom right of the door and daylight was visible through
that gap.

Recently I saw where GoWesty and VanCafe were selling a replacement spring
kit for the central lock (Bentley pic 58-267) that replaced the weak
springs with new ones.
http://www.gowesty.com/ec_view_details.php?id=23924&category_id=400&category_parent_id=
or
http://www.van-cafe.com/home/van/page_2073_1085/sliding_door_latch_spring_kit.html

The new springs solved my problem and I was able to adjust the striker pin
so the door closed tightly all around without the door bouncing back when
closed or popping open on rough roads.

While the instructions indicated to just pull back the front of the door
panel to unclip the release cable from the front sliding door lock (Bentley
pic 58-197), I completely removed the door panel.  And since I used a #3
phillips head bit with a bit adapter on a socket wrench, I did not harm the
bolt heads and reused them.

Harold

Harold Teer
1991 Westy -- VANGAUX
Harrisonburg, VA