This morning I used a new method of testing airflow and found one power supply in the corner that we missed with thermal testing.

Mezzanine:
C5-U30-RHS Stuck Fan, -24V Digital, S1201957.  Current draw is <1A, no overheating detected, it could have been like this for a while.
This supply services H1-SUS-R5 ISC SC Digital.  This is paired with the +24V in this rack.

All remaining supplies, good temperature, good airflow, no oscillations.

EX:
All supplies, good temperature, good airflow, no oscillations.

EY:
All supplies, good temperature, good airflow, no oscillations.