as determined by the delay element 157 activates the alarm 147 to alert the operator in the event that the paddle 30 and presser foot 16 are not properly positioned with the flip flop 141 in its set state there is a low signal on the lead 143 removing the high signal through the or gate 149 to the and gate 151 in this condition the only way that the and gate 151 can pass the armshaft timing pulses on the lead 113 is for the paddle 30 and the buttonhole presser foot 16 to be properly positioned in that case the movable contact 50 touches the fixed contact 42 so that a ground is applied to the lead 44 which ground is inverted by the inverter 159 to provide a high signal on the lead 161 the high signal on the lead 161 passes through the or gate 149 to enable the and gate 151 to pass armshaft timing pulses therethrough when the sewing machine is operated the first armshaft timing pulse will reset the flip flop 141 which results in a permanent enabling signal on the lead 143 with the flip flop 141 being reset the high signal will be removed from the lead 145 de energizing the needle bar release solenoid 68 if this condition occurs before the time delay period of the delay element 157 the.