So, I have had the little camera inside the tank to look at the mount damage. This is the front, where the leak is; this is the better of the two:
This one appears to show the worst leak:
This is the tap connection from the inside:
These next pictures are the two rear mounts, which don't leak:
Curious tank sealer.
So you may remember that I qualified the use of the 'Seal-All' in this application in the blog post 'Leak Test'. To effect a repair, we will start by using a small wire brush in the Dremel to clean the area to be sealed.
In goes the sealer. you can see it land from the gap beside the mounting plate - I pushed it into place with a chopstick!
So I have replaced the offending tank bolts to avoid the threads become contaiminated with sealer. We will leave it for a few days to set.