Batteries stopped charging under shore power

[Islandguy]

I store my 2013 Itasca Sunstar 27N hooked up to shore power and the converter keeps both the chassis and house batteries charged up, usually 13-14 volts. Two weeks ago I noticed the chassis had gone down to 12.0 and the house batteries were 12.7. I had shore power inside the RV, the microwave had power and so did the plug outlets. All batteries are two years old and the water levels are good.

I followed the Progressive Dynamics troubleshooting steps for their converter and it showed that it was sending over 14 volts to the batteries. The next step was to check the inline fuse/breakers. I found the fuse holder for the house batteries and it tested over 14 volts with the batteries (two 6v's) disconnected, but 12.7 connected. The chassis battery cable showed zero volts disconnected from the battery.

I could not find a fuse holder for the chassis battery. I tried to find it in the Winnebago wiring diagrams but couldn't for my year (2013). Oddly enough, the 2014 has a chassis battery fuse holder in the battery compartment similar to the house batteries.

So I need help to find this fuse holder, or other kind of fuse, or maybe a breaker?

Any help would be really appreciated. TIA.
Bob