I am in a pinch with a (possible)needed rebuild on a rear Showa shock. I have all the parts but have not figured out how to charge the shock with nitrogen. I am in Peru and there is no such thing as a motoshop around that can fill the chamber. Can i use compressed air or something else that might be available? The symptoms of the suspension is that when i put weight on the seat, it goes down just a little ways and then stops. It feels like it has about 2 to 3 inches of travel. Something is not right. This is my first ever rear suspension problem in the 25 years of bike life. Any love out there?