An apparatus (1000) includes an end
effector (1200, 2200, 2300, 3200, 4200, 5200), a first flexible coil (508, 1508), a second flexible coil (510, 1510), and a pivoting lock (1270, 2270, 2370, 3270, 4270, 5270). The end
effector includes a first jaw (1202, 2202, 2302, 3202, 4202, 5202), a second jaw (1202), and a knife (1206, 2206, 2306, 3206, 4206, 5206). The first and second flexible coils are operatively attached to an upper portion (1238, 2238, 2338, 3238, 4238, 5238) and a lower portion (1246, 2246, 2346, 3246, 4246, 5246) of the knife, respectively. The pivoting lock is pivotable from an unlocked configuration to a locked-out configuration about a pivot axis located vertically between the first and second flexible coils to inhibit distal actuation of the knife. The knife can move the pivoting lock relative to the first and second jaws along the firing
stroke.