A surgical instrument includes a proximal control mechanism having an instrument control surface. The instrument control surface has an opening through which a resilient latch arm can be inserted to engage a fixed latch structure contained within the proximal control mechanism. The fixed latch structure provides a lead-in ramp that forces the resilient latch arm onto a locking surface. The resilient latch arm is contained entirely within the proximal control mechanism when engaged. A release channel extends from an outer periphery of the instrument control surface to the opening through which the resilient latch arm enters, and provides a passage through which a release tool can be inserted to engage the resilient latch arm and release it from the locking surface of the fixed latch structure. A section of the release channel may be shaped to provide a fulcrum for the release tool.