Harpsichord string breakage

[Avery Todd]

List,

   I have our Martin harpsichord in the shop right
now to replace some broken strings. I've replaced
one 8' and one 4' succesfully. My problem is that
another 4' keeps breaking just as I get it to pitch.
The keyboard is in the correct position and the
wire is the correct one, all according to the scale
sheet that came with it.
   It's a .28 mm yellow wire. So was the other 4'
and I had no problem. Three have broken already and
I only have one left until we reorder. There might
be some the same size in our Phillips harpsichord
supply but I haven't checked that yet.
   There are still 2 other strings besides this one,
to replace. I've replaced quite a few strings over
the years and have never had this problem before.
   Any ideas what I might be doing wrong? I'm about
ready to call in a "real" harpsichord technician.
   Happy Thanksgiving all.

Avery

P.S. I've used the Prinz HT for a Vivaldi and a
     Messiah performance. By request, am using 1/6
     Comma Meantone next week for a Collegium Musicum
     performance of Italian Baroque music.