As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN LOCKING MAIN CABIN DOOR, DOOR HANDLE GETS STUCK APPROXIMATELY HALFWAY AND REQUIRES EXCESSIVE FORCE TO MOVE DOWN TO THE LOCKED POSITION. LOCKING MAIN CABIN DOOR FROM OUTSIDE HAS THE SAME ISSUE. LUBRICATED MAIN CABIN DOOR PINS AND BEARING SURFACES IAW CESSNA CE-680A AMM 12-20-40. OPERATIONAL CHECK OF MAIN CABIN DOOR GOOD AT THIS TIME.