Found a $100 Brondell Swash SE600 on eBay. As expected it arrived with a few issues apart from an internal leak (no doubt why it was returned). It turned out that the heating element for the internal hot water tank was mounted on an uneven surface (sounds like an accidental manufacturing defect?). I have never used this material (Star Brite epoxy) but the reviews seem reliable. It's as easy to make as grating cookie dough and only takes a few minutes. Easy to apply too, with enough adhesion to stay where it needs to be, at least on the dry plastic surfaces I've worked with. I left it alone for 90 minutes. That's a little longer than necessary. Now I just checked, built, reinstalled and tested it again. And it's totally waterproof. It's nice to find a water-resistant epoxy that actually does what it says on the tin. Let's see how it will perform over time, but so far so good.