A multiple needle double lock chain stitch quilting machine is provided with an adjustment or calibrating system by which the positions of loopers relative to the corresponding needles of each of a plurality of sets of stitching elements of a ganged array are capable of being precisely set. A control actuator is provided by which an operator, after observing the quality of the product and stopping the machine, actuates an adjustment control system. In response to the a signal from the actuator, a motor precisely advances the stitching mechanism. A sensor monitors the stitching mechanism position, for example, by reading indicia on the needle drive shaft, and generates a position signal when the stitching mechanism precisely in the loop-take-time position of its cycle. A controller stops the motor and activates a brake in response to the position signal locking the mechanism, including the needles and loopers, in the loop-take-time position. Simultaneously, the controller disables the stitching capability of the machine and releases service door locks to allow looper and needle adjustment, which the operator may perform. When the adjustment is complete and the doors are closed, a further operation of the actuator causes the controller to lock the service access doors and enable the machine to resume stitching.