Hubbard has been unresponsive for a few years (owner Hendrik Broekman has been in ill health, responding to neither phone calls or emails). Harpsichord Clearing House has stepped in to provide Hubbard tongues, at least. Zuckermann has recently been unresponsive as well. Perhaps they have reawakened, but their web pages say last updated in 2019.
Instrument Workshop was unresponsive for a while as well, They seem to have come back, though the supplies offered are much reduced from earlier years. Still, they have a good selection of music wire.
Otherwise, there are still several European suppliers around, in Germany, Italy and England particularly.
Regards,
Fred Sturm
"Art is not a mirror held up to reality, but a hammer with which to shape it." Brecht