The knitting machine is provided with latch detector means including primary and secondary sensor means for detecting a latch improperly positioned in a closed position and for signaling when such a condition occurs. A trigger lever (30) having a free inner end (31) is normally positioned in an operative latch detecting position (FIG. 3) immediately below the path of travel of the hooked upper ends (10) of the needles N so that a latch (11) in the proper open position will not engage and trip the trigger lever (30) while a latch (11) in an improper closed position will engage and trip the trigger lever (30). A tension spring (45) is provided to immediately move the trigger lever (30) to the inoperative position (FIG. 4) with the inner free end (31) outwardly and away from the path of travel of the needles N upon being engaged by a latch in an improper closed position. The primary sensor means includes a ground bracket (56) positioned to be engaged by the tension spring ( 45) as soon as the trigger lever (30) is engaged. The secondary sensor means includes a ground stop pin (53) positioned to be engaged by the outer end of the trigger lever (30) when in a fully inoperative position.