I'd suggest determining what company made the window, and looking online or contacting them for help and information if I could not figure out what was going on myself. There are only a few companies that make the majority of RV windows. Sometimes they have some diagrams online showing how the windows are assembled. (My RV windows are
Hehr International windows, and some of them are sliders that are generally similar to what you describe. They have field service manuals available from their website.)