Welcome to AF!!
The TCC solenoid in the TH125C is easy to get to and change. You will probably have to go to a dealer to get the solenoid but changing it is very easy. Once you have the solenoid jack the car up on the drivers side and remove the wheel and the inner fender. Directly in front of you is a metal cover that bulges slightly. Remove the bolts that hold the cover on and remove it. Put a pan under it as there will be small amount of fluid that comes out and will probably drain the entire time you have it off. Remove the bolts/screws that hold the solenoid in place and unplug the wire. Reinstall the new solenoid and route the wires. The hardest part of the entire job is connecting the wires back up inside the transmission as the space is limited. Once you have everything secured and connected, replace the external cover, a new gasket comes with the solenoid. Replace the inner fender and the tire and you should be good to go. Check the amount of fluid you lost but I doubt it will be enough to require replacement but check to be certain. Good Luck!!