What bike are you on? I.e. for R1100GS front forks loads of aftermarket Honda spec seals fit that are quite commonly available even in third World.
The best workshop in Chile+Argentina by far is M-Tec in Santiago: Home
The boss of the suspension section is called Sebastian. Contact him about your issue, he has good english and very good knowledge about Ohlins shocks. In fact his workshop got our shock re-springed, re-valved and repaired in the way that lasted. I could not say the same for the shock repair shops in Argentina (Buenos Aires), Brazil and Colombia. When I needed to service or repair my rear shock - they all blew up just moments after I got on the road again.
Thus, DO NOTs if you plan to ride for a longer time after reaching Ushuaia:
- Let your shock repaired by some wannabe who thinks he can repair it and says he has experience etc - with 75+% certainty it will blow up again very soon
- Let your shock be repaired or serviced by Colombian Ohlins dealer (ironically called "Ruta 40" - although BMW parts sales are reasonable but shock service is 100% crap - mine blew up less than 100km after being serviced by them)
I don't know about IBSA and their experience, since M-Tec is not listed in Ohlins official page anymore (although last year when we were there they were listed). But note that Ohlins headquarter personnel are another bunch of ignorant people, who simply have no respect of their company's profile and their product quality - I called and e-mailed them directly and mostly was ignored. They only blame their dealers all the time w/o seeing faults they have themselves. Personally I think Ohlins that once used to be a very good quality suspension maker is now a real mess and basically just ruins left from their product quality and long-term reliability, they just are not interested in making long lasting products anymore - bending aluminium shock bodies (compared to super-strong steel ones in the past), low tolerance hydraulic preload adjusters that blow up with stronger springs. The list of their common problems goes on and apparently Ohlins does nothing to improve it - it is much more profitable to suck money out of customers with intense-service/repeir-requiring product than to sell just one long lasting quality shock and create better company image. And unfortunately it is not just Ohlins - the same goes for most of big shock manufacturers nowadays, consumerism rules (hopefully economic decline improves this cowboy style marketing and purifies the breed
If M-Tec fails (maybe coz of the coming holidays) I would send the shock to USA for repairs with fast courier service (DHL, Fedex etc) - it will maybe take a week or more, but at least you have a working shock that lasts! And trust me on this, letting it to be repaired by some South-American wannabe shock mechanic is not worth it - I have learned it in a very hard way in my South-American leg of RTW.
In USA: Stig Pettersen Pettersson Pro Suspension uses OHLINS Motorcycle Suspensions and Forks
Reasonably priced and beats the offical USA Ohlins dealer IMHO with his personal service. I sent my broken shock to him from Colombia (after disasterous experience with Ruta 40) - the same shock still works after more than 60 000km since last Stig serviced it for me (although Ohlins recommends servicing every 20 000km).
PS: If you have to send it to USA, be sure you pay for sending it there-and-back in one shot (then there should be no import tax) or if that's not possible then declare it in Chile or Argentina's customs (from where you send it) and mark only the shock repair service cost, not the cost of shock itself - otherwise you pay 100% tax on receiving it back!
Good luck, Margus