upright flanges with threads

[Mickey Kessler]

Hi all,

The piano I was working on the other day was a quite lovely old 
Gildemeester & Kroeger upright.  The hammer butts have their own little 
return springs, held by threads attached to the flanges.  (I understand 
from one of the catalogs I have that Yamaha uses a similar arrangement.)

So -- my question is this.  A large number of these little threads have 
bitten the proverbial dust, snapped right at the center.  Is there an easy 
fix, or am I going to have to cut a bunch of new threads and somehow glue 
them in place?  What kind of thread should I use?  What kind of glue?  How 
critical is the length of the thread, or does it just have to provide some 
tension?

Any advice would be greatly appreciated.

Thanks,

Mickey Kessler