I have seen these things all gummed up. Mostly because the starter
had to be replaced and the lock stuff was reinstall without the
small protective sleave that clovers the moving parts. I have used
 heater hose to replace the protective cover. Once in place
and working, I wipe sylicone seal on the seams.

            Eric                   86-VW4x4
            vw4x4@fyi.net          72-240z
            Pittsburgh, PA USA     1936-Chrysler

On Sun, 6 Jun 1999, Tom L. Neal wrote:

> Differential lock has always worked after a few seconds for 20 or 30
> tries.
> Yesterday, inadverdently had the knob out (on) and moved the van forward
> about 20 feet straight on pavement.  Noticed the light came on, so pushed
> in the knob.  Light went off. No problem.
>
> Later got into the car to drive.  Light off.  Diff lock on.  Drove around
> on dirt and grass, forward and back, mild turns, sharp turns,  a giant
> CRUNCH signalled the return to non lock mode.
>
> Drove around normally for a while.  On dirt.  Turn on lock. Light on,
> lock on.  Push in knob.  Light off, lock on.  Drove around dirt and
> grass, straight and with turns.  A small "crunch" signaled the return
> to normal mode.
>
> Since the switch detects the shaft position, it seems the servo shaft
> is retracting enough to turn the light off, but is just hanging onto
> the lock mode.
>
> Bentley shows a shaft that almost looks like it has a flared surface
> that could be grabbed.  Mine has no flare and looks like just a flat
> shaft/sleeve.
>
> Have searched the archives and the only relevant message was a suggestion
> to put WD-40 on the shaft.
>
> Thoughts?
>
> Cheers, Tom Neal
>