An apparatus, comprising: (a) a shaft assembly, the shaft assembly including: (i) a first shaft component, (ii) a second shaft component, (iii) a joint joining the first shaft component with the second shaft component, the second shaft component being movable relative to the first shaft component at the joint, and (iv) a sliding electrical coupling at the joint, the sliding electrical coupling being configured to provide electrical continuity between the first and second shaft components while permitting movement of the second shaft component relative to the first shaft component at the joint; (b) an end effector positioned at a distal end of the shaft assembly, wherein the end effector is operable to engage tissue of a patient; (c) a control module operable to power the end effector; (d) a first sensor (1566, 1568) positioned adjacent to the joint, wherein the first sensor is configured to: (i) measure a joint parameter indicating a state of the sliding electrical coupling, and (ii) transmit a first signal indicative of the measured joint parameter to the control module; wherein the control module is configured to: (i) determine whether the measured joint parameter exceeds a maximum deviation from a predetermined value, and (ii) when the measured joint parameter exceeds a maximum deviation from a predetermined value, initiate a first responsive action. (a) a shaft assembly, the shaft assembly including: (i) a first shaft component, (ii) a second shaft component, (iii) a joint joining the first shaft component with the second shaft component, the second shaft component being movable relative to the first shaft component at the joint, and (iv) a sliding electrical coupling at the joint, the sliding electrical coupling being configured to provide electrical continuity between the first and second shaft components while permitting movement of the second shaft component relative to the first shaft component at the joint; (i) a first shaft component, (ii) a second shaft component, (iii) a joint joining the first shaft component with the second shaft component, the second shaft component being movable relative to the first shaft component at the joint, and (iv) a sliding electrical coupling at the joint, the sliding electrical coupling being configured to provide electrical continuity between the first and second shaft components while permitting movement of the second shaft component relative to the first shaft component at the joint; (b) an end effector positioned at a distal end of the shaft assembly, wherein the end effector is operable to engage tissue of a patient; (c) a control module operable to power the end effector; (d) a first sensor (1566, 1568) positioned adjacent to the joint, wherein the first sensor is configured to: (i) measure a joint parameter indicating a state of the sliding electrical coupling, and (ii) transmit a first signal indicative of the measured joint parameter to the control module; (i) measure a joint parameter indicating a state of the sliding electrical coupling, and (ii) transmit a first signal indicative of the measured joint parameter to the control module; (i) determine whether the measured joint parameter exceeds a maximum deviation from a predetermined value, and (ii) when the measured joint parameter exceeds a maximum deviation from a predetermined value, initiate a first responsive action.