I have a Macintosh 128k and it gets a Sad Mac error code:  040008

http://www.mac512.com/macwebpages/sadmac.htm

So, I think it's bad memory perhaps?

04XXXX = Memory test - Mod3 test  Memory chip failure- See Single Chip ID below

Bit  Loc  Sub Code

10   G7   0400

Sub Code:

YY0008 Trace

So Memory test failed, but I'm not sure what the Trace means.  Perhaps I just need to replace the RAM chip?  Guess it wouldn't hurt.