Water tank drain valve failure
While boondocking this past week, experienced essentially the same thing. I was able to obtain a new "close" 90 degree fitting, but have not been successful in removing the remaining broken nipple threads from the tank, so I can install the new fittings.
When I tried to remove the broken nipple from the tank with an easy out type of tool, the fitting seemed to turn up in the tank. Did you receive any responses to your post, I did not see any.
Any experiences would be appreciated, we need to get back on the road.