I just finished dealing with my slider limp lock syndrome last weekend.  I
searched the archives herein and found several references to the problem
but not any where the fixer had actually succeeded in replacing the
cause....a broken spring.

Not being one to listen to common sense or advice from others, I charged
ahead and removed the lock device from my door and started squinting into
the interior of it, trying hard to figure out where the spring even lived
before it left this world.  I prodded, twisted, turned and shined all
available lights into the works before I finally managed to figure out
where the two small holes were that held the ends of the spring - buried
deep in the guts of the lock fixture.  I dare anyone to replace that
spring!!!

I finally gave up and followed a wise group member's advice.  I slid a
piece of tubing over the lock lever shaft (after unscrewing the black
knob) which provided just enough friction to hold the knob in place and
did not prevent the electric actuator from operating properly.  It's not
the solution I was hoping for but it does work perfectly.

Best of luck,
Brent
www.weidefamily.net/vanagon/