A tissue resecting device (800), comprising an assembly of tubular first and second members (815, 820), the second member having a resecting element at a distal end thereof, a handle (806), and a motor drive system (805) carried in the handle and a controller (850) configured for moving the second member across a window (822) of the first member. The motor drive system including a motor (824) and a motor shaft (826) driving a rotation-to-linear motion conversion mechanism (828). A distal edge (840) of the second member moves back and forth across the window of the first member from a window open position to a window closed position. The controller further includes an algorithm configured to stop reciprocation of the second member with the distal edge of the second member at a stop position in which the tissue-receiving window is partially open.
