you can try this it has worked for me
Boil some water in the microwave and dropp in the atties. swirl them around a little to get them completely wet. after about 5 mins drain and do it again. then once more. after blowing them out put them in the oven after cooking dinner, with the door open to dry them come back and apply a couple drops on the bridge. chances are you will get the best flavour and vapour than I've ever had. but with everything it is all trial and error nothing in life is certain
just coz it worked for me dont mean it will work for everyone
so this is another method i have heard of
If you atty is all gunged up and wont clean easy you can try an ultrasonic cleaner but the cheapest way is just trow your dead atomisers in water with a couple Efferdent tablets you will see all the gunk rise to the top of the foam follow the cleaning with a good hot water rinse. No problems, no aftertaste, a cleans them well dry in which ever method you like either leaving over night in a hot place OR the dry burn method.
hope this helps
PS I would only clean my atty if it has stopped working that way you got nothing to loose