Progress report.
Probably different models and years had different battery supports. Mine is a stout steel tray hanging from four stout steel straps. With the teeny access door. Since my battery was shot I measured the tray to see if it would hold a Group 27 instead of a 24. And it does, just barely.
So I bought the 27. But, long story short, the top of the battery is longer than the case, because of the ribs molded onto the ends to provide some beef for the carry strap. Because of those ribs, the battery would not clear the tray hanger straps. I used a hacksaw and cut about 1/3rd of the rib off each end, leaving only the middle 1/3rd. Which does still seem strong enough to use the carry strap, but probably not all the time. Then I was able to force the battery into place, and once the remaining rib portions were inside the hangers it was all good. That battery is not going anywhere now. Whenever it goes bad I'll be sizing it up for an AGM so I can set it and forget it.
And the genset runs! I was gonna remove the carb until I saw how hard it would be. I saw there was a drain screw for the carb, and when I opened it, nothing came out. So I mixed up some Seafoam and gas and ran a fuel line into the genset. (The stuff that dripped out of the feed line from the tank was pretty stale. New gas had been put in the tank, but the genset line must have had the old stuff.) After a couple of false starts, it came to life and ran real nice. I'm going to reconnect it to the main tank and run it for a couple of hours.
Nothing on the steps yet. DW was going in and out to clean. I half hoped they would work once the new battery was in place, but they didn't.
Teacher's Pet, it sounds like we might have gotten lucky on the gas thing. Knocking on wood. Since you live over there where they were built, have you checked to see if parts and/or factory service are still available from new owners Monaco/Holiday Rambler?