Yes, the service valve can be repaired.

On my '86 there was no shaft packing, just a simple o-ring.  Drain the
tank, remove the stem nut, and unscrew the stem until it comes out.
You'll see the o-ring on the outside.  Clean it all up and replace the
o-ring.  I used a simple buna-n one found at the hardware store with a
little silicone grease on the threads and the o-ring.  I did this a
few years ago; no problems.

Ryan

On Sat, Nov 23, 2013 at 3:16 PM, Al Knoll <anasasi@gmail.com> wrote:
> Volks,
>
> Is there a shaft packing that can be replaced.  Mine doesn't leak when
> it's fully off or fully on but partway on it leaks slightly.  Any
> thoughts on replacements, this is the on off valve not the filler.
>
> Pensionerd.