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.