I finally used my 52 over the long weekend.
It leaked. Profusely. Filled my drawer with water --- twice.
I thought I hadn't closed the big cover enough so I tightened it after the first flood. 2 hours later I discovered flood #2 and saw that the little cap was leaking.
Dumped all the water before it could leak for the rest of the weekend ----- Still had ice after 3 days even with that poor practice.
Got home and gave the caps a closer look. The big cap has an o-ring that wasn't placed well so I straightened that out. The little cap has a keeper tab that goes around the threads and keeps the cap from screwing all the way down to the seal. Once I took off the keeper ring, it tightened down and didn't leak a drop.
So, anybody that has one, give your drain caps a trial run before you actually use the cooler. You might have a leaker too.