I had the afternoon off today, so I popped over to the National Air & Space Museum's Udvar-Hazy Center. I spent some time looking at their Mars Pathfinder display. Their Pathfinder is an engineering duplicate of the lander, and the Sojourner is "a nonworking model built by JPL for the NASM." One thing that struck me was that the ramps for Sojourner looked too narrow. It looks like there are metal guides that are about the same distance apart as the inside wheelbase dimensions, so they could act as a guide for Sojourner's wheels. However, there didn't seem to be enough width of material outboard of those guides on which Sojourner's wheels could safely travel or be supported. The only other thing I can figure is that the dimensions on these two display items don't match up.
Does anyone recall how that worked?
Here's a photo I snapped today, perhaps you can see what I mean.
Sojourner model on Pathfinder