I always do a pepsi bath with my 510 attys. I leave them in full sugar pepsi (its the phosphoric acid that does the cleaning), for about an hour. Then I drop the atty into boiling water and let it simmer for a minute. Take it out of the boiling water with a spoon, jiggle it around for a minute until its cool enough to put my mouth around, then blow through to clear out any water. I give it really good hard blow-throughs, then I run a hair dryer through it for a couple of mins. Finally, I get a shot glass half filled with Glycerin and drop the now dry atty into the glycerin, and blow the glycerin through . That's it. A new, clean atty - I then just wrap cling film around the whole thing till I'm ready to use it again - I have about 10 attys on rotation and I use one per flavour (5 flavours on the go at any one time).
Once I'm ready to re-use, I take it out of the cling film, lightly blow through the glycerin into a kitchen towel, then just stick a freshly filled cart on it. It acts exactly like a brand new atomiser, and it takes a couple of days to reach its full vapour power!
Since doing this I have never had a single atomiser die on me. I do it once the draw becomes harder and vapour drops off.