Problem solved!
SONICARE TOOTHBRUSH.
I grabbed a stem that had been sitting in 91% iso overnight, rinsed it off with hot water, inserted the bristles of a Sonicare toothbrush so that they pushed through the screen, and turned it on (while the stem was still wet).
The bristles of the toothbrush immediately turned brown, so I knew I was on to something. After brushing it around for about a minute, the screen was basically like new. There's a tiny amount of resin still around the perimeter and by the chunkier part of the clip, so I'm doing another iso soak before I reapply the Sonicare method once more.
The bristles rinsed off nicely, so I don't see how this could ruin a toothbrush head. Sonicare heads aren't cheap however (at least $20 a pop i believe), so I suppose it would be best to use a worn-out brush head that you're no longer using for your teeth.
I suspect that any run-of-the-mill electric toothbrush would do the trick, but the Sonicare vibrates at an extremely high frequency for more effective/efficient cleaning.
EDIT: more observations while I'm in a good mood!
When we first got the PD, we were slightly disappointed as it seemed like the only way to get nice, thick vapor was to draw extremely slowly, to the point where it would be uncomfortable on the lungs. Now, it seems like we can hit it practically any way we want and still produce vapor. Whether that's a product of simply learning how to do it "correctly" to the point where it's second nature, the wood (black walnut) "breaking in" to where it holds a slightly higher temperature, or some combination, I'm not sure. At any rate, it seems impossible to fuck up at this point, even when we introduce it to friends who have no vaping experience.
Still, I hit it basically the same way every time: a couple of "primer draws" using only the muscles around my lips to get air gently flowing, followed by a slower, longer hit with my lips slightly parted, inhaling as I go. My wife typically uses the primer draws as well, followed by shorter, harder hits. She seems to get just as much vapor using her method as I do with my method.
Speaking of my wife, who combusted for over 10 years before vaping at all (the PD was her first vapor experience) - after using the PD for barely over a month, she has tried combusting with a bowl, steamroller and joint... and now finds them all disgusting, greatly preferring the PD experience for 1) taste and 2) the fact that she doesn't feel like coughing, and that it's so much nicer on her lungs. Although she was skeptical before I made the purchase, it's safe to say now that neither of us will ever combust again, at least not willingly!
The other thing I wanted to touch on again was efficiency. I understand that the PD is more efficient than basically any other vape, but I can only compare the PD to combustion since I've never used any other vape. For combusters contemplating the PD as their first vaporizer: you will pay off the price of the PD within your first ounce (given prices of roughly $400/oz where I live). My wife and I have actually exclaimed, "are we ever going to have to buy another bag?!" The PD is THAT efficient. Keep in mind, we still haven't used anything that could be considered "top-notch," since we've only had access to mids since getting the PD. Regardless, it requires a comically small amount of material to get us "where we need to be," and we're accustomed to at least two sessions per day (not *high tolerance* by any means, but we're not weekend warriors either).