Hi,  For all threaded screw eye requirements I would buy them made
to pattern from Kimber Allen organ builder suppliers, or for piano
action work they are readily available from Fletcher & Newman and/or
Hecksher's (assuming they are still in business), chrome plated.

I certainly would not bother wasting time trying to match an original
when stock sizes are readily available and easily modified.

If they are a slack fit in the adjuster rail, then make a new rail.
Who's going to know?

Cheers from the grey skies of the UK.
Paul Camps

 [ Kimber-Allen UK Ltd., Broomfield Works, London Road,
 [ Swanley, Kent, BR8 8DF, England.
 [ At http://kimberallen.8m.net/about.html : "Our in house production
 [ capabilities include ... Hand and Machine Thread Rolling ... "
 [ -- Robbie