An undesirable intermezzo: Battery Packs are EVIL!
While looking for something completely different I had to face the following :
Corroded backplane pins near battery connector (rear of CPU backplane, bottom right)
And even worse:
Corroded backplane memory connectors (front of CPU backplane, bottom left)
I had removed the battery pack as soon as I laid my hand on this machine, but the electrolyte which leaked out of the NiCd battery had already creeped inside the wire sheath towards the backplane :-((
This means I will have to dismantle the backplane from the cardcage to clean it. I hope I can stop further corrosion at least, but I'm not sure whether the two leftmost memory slots will ever be usable again. Worst case would be that essential PCB traces are damaged beyond recovery already. I have other backplanes, but they aren't in top condition either ...
Maybe I should remove and clean the Unibus backplane as well, just as a precaution, one never knows!