Please Help - stuck on 32nd note arpeggios

[baham99]

Specifically, I am referring to bar #12 in one version of Ballade Pour Adeline where the notes are:

EG(E)G DG(D)G CG(C)G

The parenthetical notes are one octave above.

I've never hit a wall before in terms of my ability to progress through a piece. I've always been able to eventually master a difficult measure through methodically analyzing the fingering and practicing with proper technique until it I get it.  However, I feel like I can't *physically* conquer this measure.

I can play this measure without a problem as 16th notes at about 100 bpm.  However, the music calls for 32nd notes at about 70 bpm.  My technique completely breaks down at that speed.  I can play each note crisply if I move my hand back and forth (slight lateral movement) - but this makes me hit a speed wall.  I can play the note *at speed* (as 32nd notes) IF I quickly scratch or if rotate my wrist back and forth.  However, I cannot strike the keys with evenness and consistency using the latter approaches.  The middle note of the arpeggio suffers because I can't release my index finger fast enough after each depression.

I watched a dozen youtube videos of other people playing this measure.  I realized that all of them could easily reach the top note with the 5th finger without moving having to move the hand.  This is a physical impossibility for me.

My questions are:

1.  Am I stuck because my hand is too small?  I can comfortably do an octave, and can reach a 9th with some effort and only hitting the front of the keys.

2.  Am I stuck simply due to a lack of experience?  I've never taken formal lessons, but have always managed to learn intermediate pieces that I wanted to learn through persistence and commitment.  (Small repretoire though - less than 10 pieces).  I have also always made it a point to emphasize technique and musicality and never extend myself to learn a piece beyond what I perceive to be my technical limit.  Am I just not ready for a measure like this?

3.  Am I stuck (in part) due to the poor hammer action on my DP?  I haven't tried this measure yet on an acoustic (just recently bought a Privia).  Could that be the reason my middle note disappears on me?  (The key doesn't bounce back quite as fast as I would like, and unless I hit it from it's 100% start position, it makes no sound.)

Long time lurker...I look forward to the valuable advice I have observed from this forum.