Technical '37 Zephyr - Grill Trim

Anyone have any tips for installing the side moldings on a '37 Zephyr grill?
It appears that they just push over/snap on. I have tried pushing them on and they do not want to go. They are sort of U shaped in cross section. I thought about trying to spread them open slightly to loosen up the fit. Maybe more force is the answer but, I do not want to damage them. Kinda stuck, looking for advice.

 

Start from the bottom and screw it in. Then work your way up using a rubber mallet.

 

I considered that but, was hesitant to hit it with anything.

 

Get a helper to hold it while you work it up.