So the latest crisis in this saga, is that when I leave the Dometic fridge door open when not camping so the fridge does not get horrible inside by leaving the door closed, the light stays on. Didn't happen with the Norcold in the 2003 5er. Don't know why not. The light in it worked.
I pulled every fuse in the DC fuse panel and nothing happened with the fridge light. Stayed on. On shore power. So maybe when I by-passed the 6300 converter and kept the old fuse panel (doing the jumper trick you do for that), I maybe by-passed all the fuses? Can't be right. No idea.
So yet another new chore to add to the list for getting things working right in this 1991 rig. :( (I do like this rig though, so no hard feelings, really.)