I have a broken (?) rewind spring in a KD3S and
in looking up part numbers I found part
number 24-20775 is shared with many models.
(NOT KF3,KF5 or Mark 5)
So if you have a rewind assembly lying around check
to see if it uses the same spring. They are about
$30 new ,but, a good used one will work.
I suspect your WD3S may use same spring, but, only
actual trial will prove conclusive.
KE4, KD4S,KE3,KE7,KF7,KF7,KG4,KH7 Mark 15,20,20H all
use this spring so should be a lot of them available
used and usable.