Mine are the tuck-in the slot type too, don't remember where from but they have been a royal pain in the butt right from the off.
As an engineer, I turned my nose up at the "Heath Robinson " method of slipping TWO small metal clips into the window slot and expecting that to do anything useful.
I was right. One fell out in short order, luckily at home and did little damage. The driver side one would occasionally prevent the window closing properly, causing an infuriating noise in my ear, other times the bloody window would close 90% but then feel resistance and re-open... this could continue for a good while, as I got madder and madder and forced to stop, pull the bloody thing out and have to faff about with it at a later date.
Having read this article, I'm relieved to hear that others too share my pain with these contraptions, so I'm going to order some Climair deflectors right now.
Thankies for the advice! Ordered 8 minutes or so, later.