Following Robert's post about fan lines in the Darm spectrum from EX Fil and I went down and investigated cabling.  I did not like the grounding scheme on the new +-18/48VDC power supplies so we changed the connection.  The supplies are now hard wired together through the returns and grounded.  Other supplies are done this way but they only supply 2 voltages not 4.  Will look for improvement or not.