What was found
AT 220 KTS RECEIVED L/E SLAT DISAGREE LIGHT. ACCOMPLISHED QRH CHECKLIST 9.1.10, L/E SLAT DISAGREE 0. L/E WOULD NOT DEPLOY BEYOND, BETWEEN UP AND 1, USING ALT FLAPS. QRH LEAD ME TO RUN QRH 9.1.6, L/E SLAT ASYM CHECKLIST. FLAPS DEPLOYED TO 20 USING ALT FLAPS. LANDED AT 166 KTS IAW CHECKLIST. POST FLIGHT DEBRIEF WITH CREW, THEY INDICATED THAT BOTH THE L/E DISAGREE LIGHT AND AN EICAS MESSAGE WERE PRESENT DURING MALFUNCTION, AND OCCURRED AS THEY MOVED THE FLAP HANDLE TO THE 1 POSITION. THERE WAS NO MOVEMENT IN FLAPS FROM THE REGULAR FLAP HANDLE. THE FLAPS DID MOVE TO THE HALF WAY POINT BETWEEN UP AND 1 BEFORE FAILING IN ALTERNATE MODE. THERE WAS NEVER AN ASYMMETRY LIGHT OR WARNING, ALWAYS DISAGREE. ROTARY ACTUATOR, REMOVED FROM ACFT.