Found these inside a non-working 71B

[rprosperi]

I don't know if this helps or makes things more complicated, but do note that some 71's were modified by replacing (some or all of) the original 4K RAM chips on the mobo with 32K chips, and then (usually) also had additional modules wired-in as well.

Perhaps you guys are already well past considering this (I can't tell for sure) but thought I'd throw it out there in case it helps to decipher things.