In the attached an HLZ part is shown on the left, and the MLZ part is on the right. Previously in this post I stated that I'd not seen a failure mode like the one that started this thread. A disclaimer... Ive looked all over the place on the forums for pictures of failed parts. There aren't many. When Ford does a repair, we don't often get pictures. Maybe in total I've looked a 4 or 5 across several car vendors... Even McClaren and Lambo. Which is an extremely small sample. Of those 4 or 5, the failure mode is always the pin well being reamed out. And I've found patents that call this problem out. But that doesn't mean it's the only failure mode or even the dominant one. The failure mode we see on this thread is presumably, the plastic lock pin spring retainer, wears along the back plate of the phaser, and for whatever reason, disintegrates. Not enough oil perhaps. After that, the oil pressure which drives the pin out of lock, pushes it against the back plate instead of the spring retainer. And in this case it wore a slot in the back plate. The pin probably got smaller too until it either jammed, or the spring was so unaligned it couldn't push the pin back in the well.
I can say with some confidence, this specific failure mode CANNOT happen with the MLZ parts, oil or not. Note the plastic retainer for the HLZ part. The blue thing. It's free standing in the picture. It sits against the back plate at the top of the picture. It's pushed there under the constant pressure of the spring, and in operation, by oil pressure. But it's got play in the cavity which holds it. Note the MLZ retainer. It's red and you can see in on the rotor. It's not removed because unlike the HLZ part, the lock pin spring retainer of the MLZ part is press fit in the rotor. And it's in there tight! So... That plastic retainer is not in contact with the back plate and is thus not subject to wear.
I'm still hoping for pictures of the other 3 retainers. No problem if that's not possible. Just curious...
The next picture is just another view of the parts. There are some other differences but they aren't relevant in this specific case.