Are the knobs on the window opening levers supposed to have set screws in them?
 

Mine do not, and they will come off when trying to open a stubborn stuck window. There is a threaded place in the bottom of the plastic knob that looks as if it is supposed to have a set screw in it to secure the knob to the rod that raises the window.

Mine had no set screw and I lost one coming across country. Need to find a replacement.

You've hit on a pet peeve of mine with regard to these set screwsless knobs.

I suspect, in the past, these were used. Today they're not, and some knobs do come loose. Trust me, I know.

You can find set screws (with furled knobs) in hobby shops.

I called and asked Airstream about this. They do not put set screws in them any more. They told me that I could glue them on. My husband got some set screws that will fit, but we haven't put them in yet.

If you really want to make sure the knobs stay put, get setscrews (either with knurled knobs that screw in by hand, or better, slotted for a Phillips screwdriver). Also get a metal punch set (looks like a chisel, but pointed), often used for starting drill bits in metal.

Slide the knob onto the shaft without the setscrew, and mark where the hole lines up. Then take the punch set, and dimple the shaft where the mark is. Then, when you tighten the setscrew, it will tighten against the dimple, and should stay tight longer than it will against a smooth shaft where it could slip.

We modify those knobs and put set screws in them, since Airstream quit doing it.

Andy