are you sanding/rounding the area of the card below the contacts?
If you leave it square, it's going to wear the slot.
Not exactly sure where you are talking about, but...
The current version is for testing. So, no, not much is sanded that doesn't have to be.
Final production versions will have rounded corners. And, if I understand correctly....
In a side-view profile, the edge where the contacts are will be beveled at ~45 degree angle.
These two steps are necessary for the card to seat correctly.
Depending on how long it takes to do it, we may go ahead and knock off all the square edges around the entire board.