Teflon Back Actions

[A440A@aol.com]

Ed writes: 
> a 1970's D to write a proposal for major belly
>work.  It still has the original teflon bushed back action.  Are there
>any
>inate design or performance problems I should be alert for in the back
>action?  This would be the right time to replace it if justified.

Greetings, 
   There are several things that come to mind. 
    Looseness in the pinning, (clicks that are hard to repair),  and the 
short arms that were in many of these.  Check to see what kind of geometry 
you have, as I have seen several of this vintage that had the arms slanting 
so far downward that they dug into the keyend felt and added an unwelcome 
resistance as well as poor underlever travel. 
   It isn't hard to justify replacing it if you want a complete performance 
level piano. 
Good luck, 
Ed Foote RPT