I would do that after you remove the servo and only if you want to check the servo gears. It's best not to open up the servo unless absolutely necessary since you will have to deal with small pins and plastic gears that all interchange with each other.
On the bottom of the chassis, it should have a small access cover that you take off to get to the servo horn screw. Then remove the screw that holds the servo horn, take off the servo horn and remove the four servo mounting screws from the inside of the chassis to take the servo out.
It sounds like a gear in the servo is stripped. You can open it up and check the gears. I'm pretty sure that the TR-MT10E comes with a Savox servo so you should be able to find a replacement servo gear set. You can also just replace the servo with this one, which is really good and inexpensive -...