Coilovers--low nitro

I have a set of icons that have a clunk. Ive found in the past that it usually means low nitrogen. I almost have about 40k on them. What causes nitrogen to fall off? bad seals? i have no visible oil leaking from anywhere.. Would recharging the coil-overs be worth it or should i replace seals as well..

 

Would probably benefit from a rebuild. Seals for sure.

 

yeah downsouth motorsports rebuilds every shock under the sun I'd shoot them an email or PM

 

thanks.. hopefully they can sell a rebuild kit.. I cant wait for the turn around time.. I also cant imagine it being very hard to rebuild them