Here is how to do it
You need a 5mL or 10mL syringe, depending on the patients size. The syringe is placed in the mouth between the upper and lower molars of the affected side and the patient is asked to gently bite down. They are then asked to gently roll the syringe back and forth. As the molars roll over the syringe, it results in a gliding motion as the mandible slides posteriorly. The condyle moves posteriorly and slips back into its normal anatomical position.
Try it and let me know how it goes.