Neupert still sells parts, and says they will make parts for other harpsichords as well.
Here's a link to their price list. I haven't dealt with them directly, but have had customers who did.
Suppliers in the US are nearly at the vanishing point. Zuckermann and Harpsichord Clearing house offer a fair amount of what is needed from day to day, but with the disappearance of Hubbard and Instrument Workshop that's about it. (You can find some pretty flaky-looking operations if you search the internet).
Marc Vogel is probably the closest to a full-service harpsichord supply business.
Forniture Techniche Pianoforti in Italy has a fair selection (from fortepianos and harpsichords) but very pricey.
http://www.harpsichordjacks.net/ will make wooden jackets to spec or copy. There are a couple other sources for wire, like
Malcolm Rose. That's about all the suppliers I know of at the moment.
Regards,
Fred Sturm
http://fredsturm.net
www.artoftuning.com
"I am only interested in music that is better than it can be played." Schnabel