The valve body is the most intricate part of the automatic transmission. It contains various valves, passages, accumulator pistons and springs that divert the correct amount of fluid pressure to the desired apply element. Most of todays transmissions contain a variety of solenoids and many even have pressure switches. Some modern day transmissions may have the computer mounted to the valve body.
If your valve body has stuck valves simply replacing it is NOT a repair option. There is a reason the valves are sticking and it’s not just fate. There are fine metallic particles caused by failing components that are causing the valves to stick. It is important to fix the cause of failure. Not just the failure itself.