plastic flanges

[Tvak@AOL.COM]

I have a piano which I am planning to sell. which has plastic flanges 
throughout the action.  The damper lever flanges were extremely brittle and I 
replaced all of them.  They all broke in the same place:  the spring is 
mounted off-center on the flange, and it was the narrow side which broke 
consistently.  

The wippen flanges and the hammer butt flanges are also plastic,  but don't 
seem to be as brittle.  (The damper flanges would break if I bumped into them 
while filing the hammers.)  I know that the plastic in this piano was all 
manufactured at the same time (1950), and the condition of the damper flanges 
is indicative of the condition of all the other flanges, but is it possible 
that these other flanges aren't breaking because they don't have the kind of 
stress that the damper flanges have (the spring)?  Is it possible the other 
flanges might be OK?  Must I replace all the flanges if I want to sleep at 
night after selling this piano?

Tom Sivak
Associate, Chicago chapter PTG