A friend of mine is having some trouble with his 2000
Protoge. The car is a base model sedan, automatic with 108,000 miles

The symptoms are the car shifts hard and generally won't go into overdrive.

The car is throwing a CEL so we checked the numbers.
P0771 - Shift Solenoid E Performance
P0741 - Torque Converter Clutch Circuit Performance or Stuck Off

Does anyone have experience with these codes?
Is the torque converter going bad, or is there a solenoid that goes bad?
If it's the solenoid, can it be replaced independent of the tranny?

Thanks for the help.