I had some time to take it apart this afternoon, and sure enough, the elements had separated, but I think the previous owner had already had the same issue and trie to repair it unsuccessfully. There is glue, or something, on most of the prism surfaces, so I'm going to have to find a solvent or some harmless goo remover to clean the surfaces. Also, at least one of the prisms seems to have been broken - one edge is ragged. I didn't find any glass shards inside the housing, which is what makes me think this has already been monkeyed with before. But you were all correct - this bugger is easy to disassemble!
I'll let you know how it goes...
Mark