The rear latch IS the latch that holds the door to the body.  The 
handle on the front of the door actuates the rear mechanism with a 
long cable thingy (it has a special name, can't remember).  You will 
need to remove the interior latches, covers, etc. and then remove the 
cover panel to access the stuff inside.

Once inside, you'll find adjusting gizmos to tighten/loosen the 
cable.  Much like the adjusters on bicycle brake cables.  Sounds like 
the rear latch is not being allowed to completly latch, probably need 
to loosen the cable.

While you're in there, it would be worth your time to take both 
mechanisms out, clean and grease everything that moves.  In a few 
years, without greasing, the grease with thicken, increase effort to 
actuate mechanisms, and eventually work loose the pressed metal that 
holds the front handle to the mechanism, leaving you with a handle in 
you hand as you walk away from your bus.  (I have a 25 cent fix)
But cleaning and greasing will prevent this.  Sorry to rant, but BOTH 
my '80's have had this problem.

- Jeff
'80 Westi

> For the last two mornings on the way to work, the sliding door on my '90
> Camper has popped open.  In the past I've had a little trouble closing
> it--if you don't give it just the right "touch" when you close it, the
> back end doesn't seem to engage.  A little oil on the latch has alway
> seemed to cure that, tho.  Its not popping open all the way, just the
> back end pops out.  This morning I heard a faint "thunk" and then air
> noise, and when I stopped at the office it was slightly open back
> there.  Any suggestions on what to adjust, replace, etc.?