When checking the fluid make sure you check level and condition and then change it. When you drop the pan, make sure you check for the amount of metal in the pan.
If this doesn't solve the issue then we are going to have to go into the unit. So let's start with this and go from there. Let me know what questions you have.
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.