[Eliot Ness]

Those two holes were electrolytic capacitors.  They most likely removed the old ones and put the new ones under the chassis.  It's too bad they didn't re-stuff the old capacitors and leave them because they were possibly Mershon capacitors that polish up nicely.  You can see them in this thread:

http://philcoradio.com/phorum/showthread.php?tid=1031

That's a pretty nice looking model 90.  I'd replace the line cord with a cloth reproduction and then advertize for a couple of Mershon caps to fill those holes.