Hmmm, might have to try a bit of vinegar in mine. Mix 50/50 with water? I can't remember what the OP said they used.
As far as getting the crusties off the coil, dry burn is the only thing I've found that works. Blow out - run through the u/s cleaner - rinse and blow out - dry burn - rinse - run through u/s cleaner again - rinse and blow out - ready to use. Sounds like a long process, but it actually quite quick.
Update to my long soak - I had 2 stainless 510 attys that soaked about 3-4 days and I just noticed that the clear coat is starting to come off (well, looks like bubbles under the cc - not actually come all the way off yet). But, this was an especially long soak. But since they are ss, you can't tell unless you look closely and even if it does come off - no harm, no foul. [this was with 50% filtered H2O and 50% EC)