What was found
(CAN) PILOT REPORTED THAT AUTOFEATHER WOULD NOT DISARM IN FLIGHT UNTIL POWER LEVERS WERE BROUGHT BACK TO BELOW 64 PERCENT TORQUE. AIRCRAFT THEN TO OPERATE AS PER MEL 61-3. NEXT FLIGHT ABORTED DUE TO AN UNCOMMANDED AUTOFEATHER. AIRCRAFT RETURNED TO GATE. NEW AUTOFEATHER CONTROLLER INSTALLED. BUT SYSTEM WORKED OK EXCEPT WHEN THE A/FX TEST TOGGLE LEVERS WERE SELECTED TO TEST. WIRING AT THE SELECTSWITCH FOUND IN BAD SHAPE.