Hello and asking for help with HP 67 power unit

[Tapti]

This morning, I did like announced and exchanged the logic boards for each other. The outcome is, that now the maschine is running without problems and the other (previously running) now has got the problems. Ok, that means the logic board is defective. What can I do ? I inspected the board as good as I can for bad solder joints or any corrosion, but I found nothing so far. My feeling is that one of the chips is not working properly over time. Is there any chance to exchange them ? Are there spare parts available ? Concerning soldering the chips I might try asking one of my collegues from the university. Another possibility would be the logic boards of panamatik and / or teenix as far as I know (Thank you Bas !). Just from what I learned from the web pages, I would prefer the teenix option, because their board cooperates with the card reader, right ? Has anybody some experience with these modern boards ? Do I have another option for a repair ?
Thank you guys,
Stefan