That page is almost completely verbatim from MacWEEK Upgrading and Repairing Your Mac 1995, but perhaps both drew on a common source, even if they have no unanimity about which is the class code and which is the subcode. Did you note that when you get the Sad Mac is as important as that you get it? In other words, immediate Sad Mac may be hardware-related, and Sad Mac supervening Happy Mac, software-related.
Given the critical nature (and failure-proneness, especially in 23-year-old examples) of floppy disks to floppy-driven Macs, did you try an alternative boot floppy? Even if board failure is a possibility, it may be traces associated with a RAM chip, and not the chip itself, that have failed. Hence the need for examination with a glass before you pinch your nose and jump overboard (no pun intended).
de