there's a lot to digest here, and hard to put thought into it with little information to work on.
things worth noting in the OP:
-when did the issue begin? and/or when were you last printing perfectly & nozzles firing at 100%?
-what was the issue that prompted your initial "fix"?
-what did you do to attempt to fix it?
-what changed, for better or worse after your fix?
-what's test print look like? what do your dampers look like? etc. etc.
chances are, if i'm guessing right based on most of these posts written in a frenzy, to which I can sympathize because I've done it too..... is that during your attempt to replace the dampers (most likely in hopes of improving some form of degrading print quality) & you may have ruined your printhead and/or the manifold that connects the damper to the printhead.
regardless, there's a dozen potential gremlins under the hood here:
best-case, you're vapor-locked within the printhead or the ink lines.
worst-case, you need a new printhead.
but without the above questions answered, or pictures posted, its hard to make any suggestions that would most likely muddy the waters or send you on a path to further destruction