My Wurlitzer Style 145B band organ stays in tune rather permanently
when stored or used at or around room temperature conditions (65 to
75 deg. F., 50% to 70% RH).

On two occasions several years apart, extended power failures
(no, we don't live in Northern California!) allowed the band organs
temperature to drop to 45 deg. F (RH 65%).  After normal room
temperature was reestablished the band organ was out-of-tune and
remained out-of-tune (flues, strings and reeds).

After retuning (not that much of a problem) the band organ retained
it's state of tuning until the next big temperature drop.  This puzzles
me.  It just doesn't seem logical since the reeds and open and stopped
flue pipes are all tuned by different mechanisms.  It has happened
twice so it must be a real phenomenon.

Does anyone have similar experience or a good explanation?

Bill Finch