I'm not saying i know anything about what I'm about to say, but...
When i used to spray cars, we'd clean out our guns with Lacquer thinner for about 10 - 30 seconds. We'd try and protect ourselves with latex gloves, but they would be disintegrating off of our hands after we were done cleaning the guns. Have you checked with the sprayer manufacturer/s to see if the thinner your using is ok for the seals?
...aren't they supposed to be clean when your done....um...err...cleaning it?