Wow, lots of reading to do after I cut the grass.................
Did a lot of skimming through here.
I had a 601 die from a burnt wire.
Took it apart, a massive amount of gunk shaped just like the 2 bottom feed holes.
It was vaped with straight purchased PG liquid.
It appeared the wire broke just outside the blob due to having to use so much heat just before its demise.
I tried all the listed methods, not efferdent yet, vinegar, alcohol, pepsi, stronger phosphoric acid, boiling water and the only thing that had any effect seemed to be the pepsi. Maybe 10% loss? All were soaked 12 hrs then rinsed. No heating. I still see no sign of a coil even after trying Gumout, other autmotive degreasers and Electronic Circuit cleaner baths. I wouln't think of vaping anything after that. Alas , they showed no improvement.
I read an interesting note on attys dying after a pepsi bath. Since I've been rebuilding my attys I have been looking into suitable materials for wicks. Oddly enough some stated they were highly corrosive resistant to most anything other than Hydroflouric and Phorsphoric Acid. Hmmmmm...the attys that died from pepsi may have had the wicks dissolved if this material was used in them. I've never seen posted what the companies use so who knows. If I can find the ref. again, I'll post it.
Edit: This is on the possible wicking material being used. I've had a couple with no wicks.
"They resist most acids with the exception of hydrofluoric acid and hot phosphoric acid."
http://www.argosyinternational.com/datasheet/Thermal Management Systems-Eglass 10.14.08.pdf
Just an interesting thought..............