While on the subject of late Aeolians, I have discovered that on
certain 1980s Aeolians (Cabarets and Sting, Sting II; I wish I would
have taken better note of serial numbers) the piano action return
springs weaken and break.  I have replaced the return springs in a
dozen or so such pianos.  The only common denominator on these pianos
is blue felt instead red or green.  I heard once that something in the
blue dye has a chemical reaction with the medal.  I have also witnessed
a higher rate of piano string breakage in these pianos with blue under
felt.  Does anyone have knowledge and a better explanation about what
occurs with this evil blue felt?

Don Barton - Barton Player Piano Co.
Minneapolis, Minnesota