Below is the before photo of original AM Solar junction box on the roof.
We are unsure if the cable entrance glands come with the AM Solar box, but we know the cable glands on our original box did not have a rubber gasket or o-ring between the gland shoulder and the exterior box wall. We suspect that is where most of the water was getting into our original box. We also note that the AM Solar box did not have a o-ring gasket on the lid, which makes that box more of a dust-proof rather than a weather-proof enclosure.
Photo screenshot of AM Solar box for sale online below.
We found a generic project box on Amazon for $12. It turned out one of the four lid screws was missing upon delivery, and we wrote that in a review online. The seller immediately contacted us and provided a complete refund. That saved us about 1/3 of the cost for a completed new box assembly. The lid screws were zinc plated, so we just replaced all four with stainless steel screws from Ace Hardware. We found the box here https://www.amazon.com/LeMotech-Waterproof-Dustproof-Universal-Enclosure/dp/B075X11CL6/ref=sr_1_5?s=hi&ie=UTF8&qid=1545005088&sr=1-5&keywords=LeMotech+Waterproof+Dustproof+IP65 This box had an o-ring gasket around the lid and all four lid screws were outside the inner enclosure for weatherproofing the contents.
The link page screen clip is below.
OK let's look a little closer at the existing installation. A bit of a mess...
The terminal openings easily accommodated the 10 AWG stranded cables from the panels and were just large enough to accommodate the larger stranded cable going down into the coach roof, 1/0 AWG I am guessing.