What was found
BIV - FLT 407498 - ATTEMPTED SELECTION OF GEAR UP, LANDING GEAR SELECTOR HANDLE JAMMED IN THE GEAR DOWN POSITION. FLIGHT CREW MADE 2ND ATTEMPT TO SELECT GEAR UP, AND AN INSTRUMENT SCREW FELL OUT OF GEAR SELECTOR LEVER SLOT IN THE FACE OF THE INSTRUMENT PANEL. GEAR HANDLE WAS THEN FREE TO MOVE, AND GEAR SELECTED UP. GEAR RETRACTED NORMALLY. ACFT LANDED (LANDING GEAR OPERATED NORMALLY). ACFT FERRIED TO PTK. LANDING GEAR WAS OPERATED THROUGH 6 CYCLES WITH NO EFECTS. SCREW REINSTALLED WITH A LOCK WASHER.