Don't boil them. Rinse the with hot water then get some denture cleaner and soak them for 15 to 20 mnutes. I usually set the atty right on top of the bubbling tablet, I don't know if it makes a difference but thats how I do it.

Rinse well with hot water. Dry them completely. Works great for me. I had the same problem with mine. I thought it was clogged and never going to work again. I only vape sweet, sticky flavors and usualy a 50/50 mix, so my atty's get clogged quickly. After the denture cleaner it was like new again. Now I do it about once a week and it keeps them working great. Over a month with my first
tank atty and its still great. And its my fav so I used it everyday, all the time. I only use my spares while its drying. To prime it I fill a tank and let it sit upright for an hour or so. Then I refill the tank and drop 3 or 4 drops into the battery side, wipe off the extra and your ready to go.