Forward Toilet through hull valve broken

So,
The dealer came and inspected and cleaned the leaking holding tank. The plan was to reglue both forward and aft toilets with a thicker more flexible glue. Unfortunately, the forward tank won't actually open to the sea. We turn the valve but while it moves, the ball in the valve doesn't actually move at all. So, we need to order a new thru hull, haul out the boat and replace it. Meanwhile, the forward tank is now as clean as we can get it so the foul leak has stopped at least. Playing with that valve is a bad idea also as if it was to catch enough to open the valve, the boat would likely sink unless you could close it again which you likely wouldn't be able to with the broken valve.