I put 3 older, lazy DSE901 attys in an ultrasonic cleaner with distilled water. Ran them through a couple 5 minute cycles then let them dry for a day. Drip a couple drops of liquid in them, puff a few times, drip a couple more and they work pretty darned good.
I tried the ultrasonic cleaner on other attys but with alcohol. It didn't work as well.
I don't know if the ultrasonic is the answer or I just got lucky. Going to try a couple 801 attys today.
By the way, the ultrasonic cleaner came from Sharper Image. I believe they're out of business now. My wife uses it to clean jewelery and watches. Pretty slick little device.