One remedy to a clogged nozzle is soaking them in a vinegar solution. But actually I find taking a push pin, and gently placing the tip inside the nozzle from the outside, and move it in a circle like you were drawing circle inside the nozzle. Keep in mind you have to be gentle, and this does not mean stick the pin inside the nozzle like you're trying to widen the hole, you should not force it inside, just enough to scrape out whatever is just inside it.
-Dave
SmallPetFeeders.com