I've never seen an IMSAI before in-person. The
front panel does
 not have the white "IMSAI 8080" logo. You can see a silhouette
 of it under the Plexiglas mask. Does the logo light-up when turned
 on? Maybe this is a replacement mask (although the screws do not
 appear to be disturbed)? 
If I recall correctly, the "logo" is composed of two parts, one is a
clear plastic sheet with black printing that gives the shape of all
of the letters, switch and light legends, etc.  Behind that, there
should be a sheet of foil backed white paper.  Those two sheets are
sandwiched between a sheet of clear and red Plexiglas.  Sounds like
you are missing the white sheet.
Bill