Is your hand above, on or below the equator of the ball as you release it? For more revs, you need to get your hand a little underneath the ball, get your thumb out before your fingers, and roll the ball firmly off your fingers. Don't let your fingers bend backward as the ball rolls off them.
Have you tried cupping your wrist a bit, or does the wrist guard lock you into one wrist position? Sorry, I'm not familiar with the support you use. Cupping your wrist helps get your thumb out sooner in the release.
Where is your PAP in relation to your grip midpoint? IOW, do you have a low track, normal track or high track? If you track low, you need to concentrate on staying behind the ball, and letting it roll, moreso than if you have a high track.
I'm not a coach, but like you, I'm always in need of a few extra revs, as it doesn't come naturally to me.
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seadrive
Cogito ergo bowl