For those of your engaging on your own repairs, here’s some places to get the tools and bits you need. This list is purely alphabetical; I put an asterisk next to those I’ve gotten parts or tools from, which you may take as an endorsement; I’ve yet to feel I’ve been ill-treated in any of these transactions. Lack of a * just means I haven’t tried them out yet.
The Classic Nib (more in the line of components for modern pen turners than replacements for vintage)
Tryphon (this link is left in place on the grounds of optimism; Tryphon appears to have given up on the parts side of the pen business)*