[Tapin]

We've got Aerons at my office that are years old -- unfortunately, it seems that at least for the chairs here, once the arms start to slip you're pretty much SOL. The track and clamp have worn down, and any attempt to shim the arm tends to make the track wear down faster.

(Of course, if anyone here happens to come up with a better solution than shimming the arm, I've got about a half-dozen chairs here that might become usable again)

Edit: Nice avatar -- the benjies next to the dirty clothes and Target bag are an effective contrast ;-)