Yes it is probably the regulator.
At the wood grain finish on the door panel, right in front of the door pull grip, you put a feeler gauge between the wood and the leather, Move it in about 1/2" and then slide it up. This will unlock the catch. One on top and one on bottom. After that you remove all the screws,3 of them two behind the wood panel one inside the arm rest. Use a flat head to pull up the plastic trim piece. Then easily pry off the door panel around the edges. Be sure and get the little screw at the door catch. All else will be self explanitory when you lift off the panel.