I (likely) have the same issue. One of my "winterizing" drains broke off and now it leaks water when either we are hooked to a water source or turn on the water pump. We tried to back out the broken piece from the drain but that didn't work and now the back out tool is stuck...argh
We are storing the trailer at a place with service folks (general, not airstream specific) and while they will take a look, they have a bit of a backlog. Unfortunately I think the fix will require dropping the pan covering the bottom of the trailer then fixing the drain that broke off and likely the second drain next to the one that broke.
The suck part is without this getting fixed, we have no water at all in the trailer. We went camping last weekend, we really want to get this fixed before taking it out next time. I'm also in the bay area (pleasanton)