Something new that I just noticed/had to deal with…
I took my handle back to my supplier because it wouldn’t unscrew to take an Unger channel again. There is a definite difference in width between the two channels, so the screw setting makes this easy to adjust, but after lots of head scratching it seems like Unger has actually (potentially intentionally) designed the thread to sort of strip out at the exact depth you need to adjust it to clamp to an Ettore channel.
Thankfully my supplier loves me and he just gave me a new one for free and sent the used one back to Unger as defective. We later realized it wasn’t just that one handle but a design flaw (or feature, if you’re Unger) in the handle itself.