Are you trying them within the housing? Or just trying them loosely on the wire (as shown in bottom photo) to see how they fit?

It is important to know that the 'box' on this contact does not fit over the pin - the box holds the contact in the correct place within the housing. It is actually the two serrated wings that fit over the contact and actually hold them fairly tight. For me - much tighter than the trifurcon style.

I just did a side by side between the two. For me - the high current has a bit harder insertion and extraction forces. Not a lot tighter (as I mentioned above) but enough to notice.

As far as I can tell - the crimps look ok (the wire could have been trimmed shorter but that doesn't affect insertion/extraction force as the extending wire sits to the side of the contact area). I was thinking maybe the two wings had been spread out. But if I remember correctly, the connector body would force them back into alignment.

Something else seems to be at play here. Maybe the headers on your machine are slightly smaller than standard Molex/Pancon/AMP headers??
Molex 0.156" headers - the posts are supposed to be 0.045" (1.14mm) square.
Pancon's were often used on Williams boards and these are same as Molex at 0.045".
AMP also had the same size as Molex and Pancon - so that covers the main sources.

Take a look at the attached image (from yours). I circled the pin 'retainer'. When inserted into the plug and the plug is installed on the pins, this retainer holds the top of the pin back towards the body of the pin and keeps the pin within the middle of the serrated edges. Retainer in photo looks intact. Looking at the wings when zoomed in, they do look like they may have fanned out a bit. Maybe squeeze them in? But as mentioned above, the connector body typically forces these back into position.

Beyond that - I don't know what to say on this one.

TheBox (resized).jpg