The caps on the WRM do seem particularly hard to remove, I tried but I wasn't game to force it. If anyone has a better idea of exactly how to remove them without damaging the cube I would love to know!
However, I have had luck with putting a small drop of super glue into the slot of the magnet adjustment system, where the screwdriver goes (or the little plastic tools that no one uses). I used a needle to take a very small amount of glue that I'd squeezed onto a surface, and kind of pushed it in. As it dried, some of the glue bubbled up, so I wiped it off, keeping the surface even. Obviously the magnet can't be adjusted any more, but it's not clicking (and I've had the cube long enough to know that I like setting 1). Of course all necessary disclaimers, this is just what worked for me and I've only tried it a single time, so processed with caution!