2003 Hyundai Elantra GT

My car is stuck in 3rd gear and the CEL is on. Took the car to the local Auto Zone and had them check the codes. The code that came was P0750 which after doing some research points to a bad shift solenoid A. What would be easier or the best way to fix this? To either replace the solenoid or to replace the entire valve body? Also I wouldn’t know which solenoid to replace because I haven’t found a good diagram to go by.