Repaired as partial Christmas gift to my girlfriend, learned about winding springs and making convincing looking replacement parts.
Before
After
I wish I took a better quality photograph for the before image, but oh well. The latch was there, but the spring which flips the latch open has been gone for a long time – and there was no button to loosen the latch from it’s closed position so it required a pencil to be inserted into the hole to get to the soprano.
I resprung the latch and built a replacement part that looked fairly good by the end of it.