Is your gen set on a slide ?
If so can you run it forward , then get under and behind it to check and see if there is an access panel, for the step cover mechanism.
Also looks like a panel in the top step , what's under there?
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.