sliding window questions

[rossboss]

I've got a few questions concerning the rear slider window. On the rear slider portion of the rear set of sliding windows the glass offsets up about a 1/2". Lodged in that area I found this short piece of stainless with a piece of rubber stapled to it. I haven't any idea what it's for or why it's there. By looking at it I'm pretty sure it has something to do with why the glass offsets up. Does anyone know what it's for or why the glass offsets up, all I can do is scratch my head. I've attatched a few picture to give you an idea of what I'm talking about.
I'm in the process of rebuilding my sliding window frames. The frames are in excellent shape but the glass run channels and the pieces of beltline are really bad. Has anyone rebuilt these before and what did they use part numbers would be helpful.