Here's a new take on an old problem. I followed the other thread where problems with the memory slots on the old Toshiba Tecra 8100 were gradually losing contact with the mobo, and some had found a temporary solution - placing a piece of paper over the memory module to provide more pressure directly towards the motherboard. For some, it worked (for a while), and for some, it did not.
I've added a new twist to this solution, which I am now in the process of seeing just how long it will last. Instead of using a piece of paper, which will become compressed over time, and also flatten by the heat generated by the memory module, I've used plastic - specifically an old credit vendor "loyalty" card - like the ones stores issue - cut into a three equal pieces, and taped together with electrical tape. I now have access to both the A and B slots, with full use of my brand spanking new 512MB of RAM. Now, to see how long it lasts...