HP33E keyboard short

[workspace]

Hi everyone,

a friend of mine gave me an HP33E, which he found in the dustbin (Recyclinghof in german :-) ). After cleaning the battery compartment it worked connected to a 3V power source. Unfortunately the second digit don't lit up, so I dived in the forum archives, found a way to open the calculator without damaging, cleaned all contacts replaced the power foil connector with a cable and put all together again. The digit lit up ... but, what is that, if I press 7 I got 4, - I got + .....

The fourth row seems to be shortend to the third row. I took it apart two times more, but can't find the short.

Is this happend to someone else as well?

I really like the led display and the slow speed of the calc - you can show actually that it works :-)

I appreciate all hints and tipps to bring back the keyboard working again .-)

Cheers
Ralf
[Edit logical typo]