242B Seafoam Ball Nut questions ??

Hello everyone.
I have a question about ball nuts.
The image is a 242B Seafoam ball nut, but I saw the groove indicated by the arrow for the first time. What is this difference? Mistake in the factory?

Thank you,
Junichi

 

I assume these are Colemans made in the Toronto plant. I think they are fine, no problem. Over the years that ball nut kept changing. I think it may have had to do with the supplier, maybe (?). The US made Coleman lanterns, I don't believe came with that type ball nut.
Someone will correct me if I'm wrong.

 

Thanks for george's reply. I think Toronto Canada lanterns abound. Maybe it was the first lot or a replacement. It is a great discovery for me.

 

Thanks for george's reply. I think Toronto-Canada lanterns abound. Maybe it was the first lot or a replacement. It is a great discovery for me.