My xeno mech seems to be making a lot of noise when extending like something is too tight / loose in the adjustment.

1. How to remove the xeno head.

(you will need a phillips screwdriver for this)

locate screws on both sides: Picture shows right side.

And left side.:
 

The screws needs only to be loosen, but no need to take them all the way out.

Now it should be easy to remove the head. (lift it from the back and forward) Be carefully, the teeth are weakest part on the xeno, and dentists are expensive! 

2. Check if the 2 bolts are tight.

3. If not you will have to press down the nylon block and tighten the bolts. Also when doing this run the tongue with your other hand to feel the difference. And tighten it, check that the gear is moving nice.

4. put the skull back on, like you put on a caps on" and tighten the screws on both sides.