HP-65 more on the card reader

[albertofenini]

I think you are right, A could be the candidate,
However, what fails me is is the following.
Once the upper left corner has gone past the switch i.e. 3 o 4 mm max, there is no difference between a protected card or a non protected card, since the shape is same.
What I'm trying to say, is that the difference between a protected card and non protected card is what ? that switch closes (or open ?) a little before o a little after ?
How can I catch that ?
take care Alberto