can you if you have to and your only other choice is to buy a new one= hell yes
its fairly simple if you read the tutorials, pay attention to how things come apart, remember which way they go back together, and don't lose the 2 little tiny tiny pins on the inside. I've torn apart many many noids, saved quite a few, trashed my first because I lost a pin....but now I know...
very simple once you've done it. even simpler when you read the turorials
Dont bother tearing into the noid if you dont have too. Its not super difficult but it does require extra care and awareness. It should only be a last ditch effort to solve a problem like BAD inconsistency, puffing (no bolt movement) leak out the noid.
Remember, these problems are not just noid related and usually they are caused by something else. Rule everything else out first. Its not often you find an Intimidator or Marq owner talking about how they tore into their noid, because its very rare that you have to.