1997 MIT Mystery Hunt Puzzle 14 Solution

Several letters appear only three times in the set of letters. These three must be three words crossing at a single instance of this letter in one of the word cubes. These can be used to reconstruct the cubes (shown below in a likely order of reconstruction):

JAM PGA LON
OBI ROC EWE
TAX OPT EEC


ZOE ALS GDP
IDS VIE ERA
PDQ ADE LED


CPU PEZ ARI
HUN USA DEM
ENO TSP SAP


EGG TNT CUE
TAP ITO AFT
AMA SHY POE


TOM ALI DEA
MCI RAN ILK
CTR CSN SKA

The central letters can be rearranged to spell the answer, IOTAS.