A CESSNA 414 ACFT WAS RELEASED FOR SERVICE WITHOUT ACCOMPLISHING A MAIN LANDING GEAR SWING AFTER L/H GEAR 'UNSAFE' LIGHT ILLUMINATED ON INBOUND FLT.

Narrative

I WAS CALLED OUT TO CHK A CESSNA THAT I BELIEVE MADE AN EMER LNDG INTO ZZZ ARPT; DUE TO A L MAIN GEAR UNSAFE LIGHT. AFTER ARRIVING AT THE ACFT; I INSPECTED THE L MAIN LNDG GEAR ELECTRICAL CONNECTIONS; AND CONDITION OF DOWN SWITCH AND LNDG GEAR IN GENERAL. IN LOOKING AT THE COMPONENTS; I DETERMINED THE INTERMITTENT PROB TO BE A DIRTY AND OILY DOWNLOCK SWITCH. I PROCEEDED TO CLEAN THE SWITCH AND FOUND THE SCREWS HOLDING THE SWITCH IN POS WERE NOT TIGHT. I FINISHED THE CLEANING PROCESS WITH ELECTRICAL CLEANER AND MOVED THE SWITCH SLIGHTLY CLOSER TO THE DOWN POS IN THE HOLDER AND TIGHTENED THE SCREWS. I WAS NOT ABLE TO DO A GEAR SWING DUE TO LACK OF EQUIP AT THIS ARPT. I WOULD HAVE PREFERRED TO DO A LNDG GEAR SWING TO CHK THE SYS AND BE SURE THE LIGHTS WORKED PROPERLY. ALL 3 DOWN LIGHTS WERE IN THE GREEN POS WHEN I FINISHED. IN THE FUTURE; I WILL INTEND TO HAVE JACKS BROUGHT TO THIS ARPT; OR OBTAIN A FERRY FLT TO REPOS THE AIRPLANE TO A PLACE THAT WE HAVE THE FACILITIES TO PERFORM THE REQUIRED TASK AND TO ASSURE THE JOB IS COMPLETED CORRECTLY.