I would imagine that the company would have replacement parts.  Teddy 
Lancaster might be able to tell you (RUN4BEAR@aol.com).
Diane @ Safe Haven
On Mon, 1 Apr 1996, Linda Flemmer wrote:
> Last year, I bought a pair of Trail Tech stirrups in hopes that I 
> might be able to ride more comfortably.  I have had surgery on my 
> knees, and do not have all of the ACL anymore.  Consequently, my 
> knees hurt when I rode to the point that I was crippled at the mid 
> point.  I was afraid that they would be a gimmick, but these stirrups 
> REALLY helped!  (They took a little getting used to - it felt as though 
> the stirrups were "running away" from me as I posted.  I don't notice it now.)
> 
> I am wondering how much life I should expect from the rubber donut 
> that compresses at the top?  I am a heavy weight rider, riding in 
> them for about 40 miles per week in addition to monthly 50's during ride
> season.  Is this a replaceable part, or do I need to buy new stirrups 
> each time?
> 
> Does anyone have long-term experience riding with these stirrups?
> 
> Linda Flemmer
> Blue Wolf Equestrian Supplies/ Blue Wolf Ranch
> Chesapeake, VA
> 
>    "In case of emergency - Fur side up, steel side down!"
>