Hp41cv display behaviour....

[isanchez]

Hi,
I am building an HP41cv from many spare parts ...
The thing is that i believe I am close to have an operational one, except because it has an strange behaviour...
When I keep pressed any key I can see it in the display, but when I release the key, it disappears...the logic works, but it is not shown in the display....I am thinking in the compatibility between the display drive and the board....can you put some light on this?
I have around 12 boards, with different codes, shapes, etc. the posts are very broken, so i cannot make many tests...each time I have to fit it carefully to make good contacts...
The display drive looks with two dark grey, nearly black, rounded spots. I have set all the connections, except the first. There are three of four connected, in the more left set.
I thank you very much in advance for your help.

Kind regards