What was found
UPON CLIME OUT 4000 AGL NR 2 RMU DISPLAY, NR 2 COMM DISPLAYED DASHES, NR 2 TRANSPONDER DISPLAYED DASHES, NR 2 TCAS DISPLAYED DASHES. NR 1 RMU DISPLAY, NR 1 TRANSPONDER DISPLAYED DASHES, TCAS DISPLAYED DASHES. ATC REQUESTED IDENT FOR TRANSPONDERS CREW SWITCHED BETWEEN NR 1 AND NR 2 WITH NO RESPONSE FROM TRANSPONDERS. CREW CHECKED NR 2 COM WITH NO RESPONSE. CREW REQUESTED ATC TO RETURN TO ORIGINAL DESTINATION AIRCRAFT LANDED WITH NO ISSUES. PERFORMED TROUBLESHOOTING FOUND A PASTE LUBRICANT ON THE COAX CONNECTORS CLEANED AND RE-SEATED NAV/COM BOXES PERFORMED OPERATIONAL CHECKS AND TDR CHECKS WITH NO DEFECTS NOTED AT THIS TIME.