More on Hand Position

I have some computer problems so am not able to make recordings, but am playing as much as I can. I am working on Debussy’s Dr Gradus from the Children’s Corner. I have not been satisfied with the video I posted of that piece.
The challenge in Dr Gradus is to play the rapid notes evenly (no lumps) and with lots of dynamic shading…elements my recording is missing!
The problems I have had with hand position are either a tense arm and wrist or flat, floppy fingers. My recording shows the floppy finger problem.
I am working on keeping my hand position relaxed but firm, and moving the hand right over the keys with the arm. There is a really strong feeling when the coordination works, I feel totally in control, but am not scrambling to get the notes.
The metronome has helped a lot by keeping the pulse. All the little notes fit in when the pulse is strong.