I had the same problem, got the replacement kit but chickened out and sent
the AD5 to Cane Creek for overhaul.
Very glad I did - rapid turnaround and works like new.



> My shock absorber has gotten so it will not hold pressure, so I ordered a
> gasket set from Cane Creek. It looked simple enough, but I was unable to
> unscrew the piston. Cane Creek advertises a spanner wrench for this
> purpose for $40+, but when I called a very helpful person advised me that
> they are available at most bike shops at a much cheaper price. My local
> dealer said he could order one for me for $6, but loaned me one for the
> shop which I returned the next day. However, I could not loosen the piston
> even with a suitable wrench.
> Cane Creek does have a replacable piston for $50, or you can ship your
> shock to them and they will overhaul it for $80.
> They no longer have available new AD5 shocks for the Bike E, and their
> current shock - the cloud nine looks similar but I was told it will not
> fit a Bike E.
> I am planning to ship mine for overhaul and will post the results, but
> wonder if anyone else has had experience replacing gaskets on the AD5 or
> similar difficulties.
>
>