I've heard a few gripes about seals shrinking when stored dry for several months. Then they leak for a few minutes til the fuel swells them back to size. Nitrile is supposed to be compatible with ethanol but I'm thinking it is time to go to a better materiel (Viton). Viton is more compatible-er than nitrile.
So, I am in process of sourcing all the seals from my supplier right now. We'll see how availability and price work out. They will cost more of course. More on this as info comes in.