threads in wippens

[Jean and David Weiss]

List,

I'm working on a 1930's Harrington baby grand.  It has the type of wippen
where the springs are held in place by a thread.  About 10 of these threads
are broken.  No big deal to fix them, but I'm wondering what to expect in
the future.  How long can these threads last?  Should I go ahead and replace
them all, or just fix the 10 already broken and move on?  Is it like the old
plastic elbows, where once a few start breaking you know they're all going
to break?

Thanks,

David Weiss