Hello,
We've encountered this issue previously and found that older operators have always had this problem. The black collar would wear out and the handles would become loose, eventually just falling out on their own. As a result, the manufacturer actually ended up changing the design of how these work.
We cannot offer a replacement for the collar but our 39-226 can still work for you, however it will only be a temporary measure. It will fall out eventually. Some ways around this are using glue to hold it in, or even just packing it out with scotch tape so it's a little tighter. Again, these are all temporary measures.
If you're not in a pinch and you want a more long-standing solution then you will want a new operator. We have more modern styles that will work much better. Before I recommend anything, though, I'll need to see a photo of the complete operator with the window open so that the arms that move the sash are fully visible. Thank you!
