hi Doug, I hope you can find out about that specific part like on the Tiagras. We had some Microshift 9 spd shifters on a small road bike I sold a few years back, but I have no recollection about that part.
My cross bike similar to your volpe has the old 9 spd tiagra shifters, and frankly, if they break, I would simple to to ten speed shifters. Microshift or something, but just because I know my 9 spd bikes rear hubs can easily take 10 spd cassettes, but not 11 spd, so it would be an easy switch to 10.

Ive even thought of converting my Troll to ten speed also, but just never get around to doing it.
I like the idea of even with the same cassette range, having slightly closer ratio shifts.
I think I would like to try a 11 spd double sometime for a touring adventure bike setup, with a 40/26 or thereabouts, but am still really happy with the versatility of our triples.
Oh, and going to ten spd I think would be fairly confident that our 9 speed era cranksets and chainrings would work fine with 10 spd chains (but would have to really confirm that)