The evaluation of the movements in the opening and the proprtionality with the lateral movements (4:1) is going to give you a hint about the position of the disc and his possible reduction. If in the opening you have deviation to one side, it's possible that the disk can't be reduced and stops the traslational movement in that side.

One of the most importants procedure in TMD is to stretch the joint capsule using slight forces. With this the pain will relief enough to relax the elevator muscles. Also you can use the relaxation reflex of the elevator muscles activity touching with the tip of the tongue the palate and doing the rotational movement of the opening movement (10 mm), this is before the mandible condyles move outwards with the gliding.

The reduction of a luxated disk it's more possible if the reduction click occur on the first 10 mm of the opening. With Wikipedia reference-linkMRI you can asses if the disc can be reduced in protrusion movements, if the condyle can locate under the disk in the mid section. Then you can try to move backwards with the disc to a condyle centric relation position.

So, the first step is to reduce pain. And then without pain, try to restore the normal movements relationaship using mobilization techniques and propioception exercises.