Atari Inc carts that don’t fit in heavy sizers?

[ianoid]

Do some Atari branded carts or cases not fit in heavy sizers? I seem to recall seeing something about that a while back.

 

My main issue with with my Testcart that I got many years ago not fitting in my heavy sixer, which came in a harvested Atari shell. I’ve taken the cart apart and messed with it, but I suspect that the board and slot are incompatible. 

 

I’ve been using this Testcart for literally decades and this is the first time it just doesn’t seem to fit in a system without being removed from the case.