10 years of use, that thing owes you NOTHING at this point. But were you running a water softener or filter before it? Because hard water sediment builds up FAST and turns into rock inside the lines. I just had to replace a bunch of fittings on my old one from northern Texas because the calcium literally caked everything solid.
10 years of use, that thing owes you NOTHING at this point" - okay but still, 10 years is crazy impressive for a water heater lol. I didn't even know they could last that long without something major breaking. The calcium turning into rock inside the lines sounds absolutely brutal though, I'd be so mad finding that mess.