not necessarily, Again, I've run NR-4 and 5's for years without too many  issues.

Take the shock off the bike, remove the spring and test the compression and rebound, if both work, then it's got at least some charge.

I have had two NR shocks fail on me; one lost it's nitrogen and oil, probably a failed seal, it did not rebound after a compression; the second failed fairly catastophically, the shaft siezed in the compressed positon and won't budge at all.

Col.