Once installed the white piece is supposed to stay behind on the heater core. It spreads to slip over a metal lip but then won't come off unless you spread each ear (I used two right angle picks)
I can still send you this and a second if you want to toy around with the white retainer.
Really -- and, obviously -- the question is which is not happy in your setup? The black windows or the white ears that engage them? Honestly I'd guess the latter as that's technically a moving part that needs to "spring" open a bit to stay engaged. The black windows just exist.
er, edit to actually attach a photo!
I can still send you this and a second if you want to toy around with the white retainer.
Really -- and, obviously -- the question is which is not happy in your setup? The black windows or the white ears that engage them? Honestly I'd guess the latter as that's technically a moving part that needs to "spring" open a bit to stay engaged. The black windows just exist.
er, edit to actually attach a photo!