This has got to be the best post I have seen on the subject anywhere. Not only do we finally have a look at what it's actually like under there, we have a fix! Thanks, OP!
Now I won't avoid leaky tanks on eBay/Craigslist.
Edit: @
Z1R rider
Will this do the trick?
http://www.ebay.com/itm/Rotary-Spot-...item5660c56f72
Is it the right size?