Transgo TF2 on a 904 is not shifting

Sometimes valves stick when they get hot because the fluid thins down. Other times valves stick cold and free up hot because the aluminum valve body expands. Use polishing compound to clean a sticking valve. It's not the valve; it's the bore. Scratches make it smaller by particles gouging furrows into the aluminum. I think you put a spring on the wrong side of a valve somewhere. Post pics of your valve body disassembles.