Oh well, at least with the Alltek you've proven the plugin connectors to the MPU are ok.
You might still find the pins on the original MPU board are dirty/corroded & need replacing, but then again they might also be quite clean and usable...
Yep, SS boards are a big step from 'relays' in an EM....it takes time, but soon you get to realise that all the chips are nothing more than a collection of small relays ;-)
MM
