What was found
(CAN) AFTER TAKEOFF LG WOULD NOT RETRACT, THERE WAS A WEIGHT ON WHEELS, WOW, MIS-COMPARE MSG. ACFT RETURNED TO MX. THE NOSE GEAR WAS SERVICED & GEAR SWINGS COMPLETED WITHOUT FAULT. THIS FAULT APPEARS TO BE THAT THE NOSE GEAR IS NOT EXTENDING ALL THE WAY AFTER TAKEOFF & NOT MAKING THE WEIGHT ON WHEELS SWITCH. THIS IS THE 3RD TIME THIS ISSUE HAS COME UP WITH THE CITATION 680 ACFT WITHIN THIS COMPANY. A REVIEW OF THE SDR DATABASE SHOWS MANY OCCURRENCES OF THIS ISSUE. PREVIOUSLY WE HAVE INSTALLED SL680-32-8 IMPROVED SEAL KIT FOR NOSE GEAR.