Does this Zip Chip have the SRAMs showing underneath?

Either way, it's just a hybrid- you may be experiencing a poor solder
joint on one of the leads. You could try digging into the material on
the underside- some of them were silicone seal like where you could
peel it back. Reflow the solder on all the leads. They are leads stuck
to the side of a ceramic similar to how the 30 pin SIPs had leads
stuck onto SIMMs.
--- SBBSecho 2.12-Win32