HP67 - can be programmed but then does not work

[ovalsa]

Hello,
I made some further research - the problem is clearly in the ROM/processor board (I have the second fully working HP67 and this board shows the same problem in both of them when the other board works everywhere). Is there any possibility to analyse / fix the problem ?? I am still struggling with throwing this nice piece of history into trash bin (but what else can I do with the calculator which does not make any calculations ??).
Any recommendation will be appreciated.
Ondrej