Well, I managed to find the ladder piece, after I did a little digging into the savegame. (Which, until now, I had not realized was XML. This made things a little easier.)
The ladder pieces had somehow fallen though the floor and were just falling in space. I was able to move them back into the room by editing their transformation matrix. How they managed to get outside the level geometry I do not know, but it was frustrating to not be able to progress because of a glitch. This glitch could be compensated for by returning objects that fall out of the level back to their original starting place.
I also recall during an earlier playthrough another place where I got stuck. The mine cart you have to push downhill to crash through the brick wall somehow jumped its tracks and didn't make it down the hill. I had to reload my savegame and do it again. Also, the refinery just before has an issue that could keep the game from progressing.
There's also another glitch I found that's potentially gamebreaking, but I am hesitant to post it publicly as it's a real whopper of an exploit.
Ok then, I'm off to break the game some more.