You can't easily replace the spring, it's in the pressed and riveted housing. What you can do is unscrew the locking knob and slip a bit of rubber hose over the threaded boss. Size the tubing so that it gives a bit of friction when the knob is screwed back in. This will keep your knob up when you want it up, and down when you want your knob down.

Alistair

> On Dec 15, 2014, at 10:09 PM, Richard A Jones <Jones@COLORADO.EDU> wrote:
> 
> Mr Bus, my '81 has lost the "click" in the sliding door
> mechanism between "unlock" and "lock."  Before, when
> using the key or flipping the little lever inside,
> there was a definite "click" between the two states.
> Now, slop--and it will "fall" from unlocked to locked
> while driving, since there is no click to keep it up.
> 
> I've looked at Bentley, ETKA and at the lock with a
> mirror and I can't see anything, but I can feel what
> the button moves and that it is all slop.
> 
> Does anyone with experience with an early version of
> the sliding door lock know if there is a spring that
> has failed and can be fixed?  Or is the problem inside
> the lock box and only a new one will fix it?
> 
> Thanks for any experience with these locks or this
> problem.  Of course there are duct tape and bungees....
> 
> Richard