[urq] Diff lock actuators: anyone has repaired?

[Fluhr]

>Both diff lock actuators (857 711 995A) on my car suffer from a leak at
>the little rubber boot. The diaphragm is OK, as well as the plastic body
>and both vacuum nipples. Audi wants 255$ for each one. 
>So anyone has an idea how can we re-seal the plunger with the body ? 
>What we need is a "shrink tube"-like material that keeps its suppleness
>over and extended temperature range. 

Not the best option due to longevity, but my father repaired my
actuators by using a balloon.  It is one of the skinny types used
for twisting into shapes (animals, hats, etc.).  He put pull-ties
to hold it in place, and the actuator now works perfectly.  The
down side is that he has to replace the balloons every year or
two.  That stinks, but maybe a more durable ballon exists.  On the
plus side, $0.69 for a bag of 50 is pretty low on the replacement
cost spectrum.

Regards,
Eric
'82 urq