on the 401, i put the exposed bridge right in the flame for a few seconds, pulled away for a few, then back in the flame moving it around a bit, and yes, it did make some soot. i just dabbed the bridge with a paper towel to get the soot off. then i put one drop on and tried it. after seeing that it worked significantly better, i did it again. and better still. now the 501 is recessed, as you probably know. so with that one, i held the
threaded end with some tweasers and held it open end down and lit the lighter. I moved it around some, trying to get the flame inside a little (this was all purely experimental mind you) i did this for about, i dont know, maybe 10 sec. or less. more soot that i rubbed off the outside, and q-tipped just inside. i dont know if there was any soot on the bridge, couldnt really see, but i dont taste any. I had tried the dry burns on both of these, it worked in the past, but wasnt working any more, plus my burn is only 3.7v (a higher voltage might have had better results. now im not saying this is the latest and greatest idea, but as a first experiment, it worked for me. im going to play around with it more when i have some more dying attys, but for now, they all work. bummer right! no more to test. (edit- i should also mention that i drip, so if you try this be aware that you might fry your wick)