I bump this one as I am looking for the same answer. Could anyone point me in the right direction of where I can find a crown for this model? It is a tap 12 stem.
Depends on where you live but here in the UK, we have the database of spare parts provided by the watchmaker's guild. Similar organisations might be found elsewhere, where you can track the availability: https://watchparts.org.uk/cgi-bin/watchparts