Kanji that just won't stick

Been using Anki to rep Remembering the Kanji for the past couple of months. I'd say I'm doing pretty well so far, about 600 kanji deep and an 85% maturity. That said, there are a few super stubborn kanji that just don't seem to stick.

Curious to hear any tips/tricks for those stubborn kanji. What do you do when they just don't stick?