I can certainly understand you frustration with this issue. If it were a simple stuck valve in the valve body. The problem is easy to find IF the there is an actual "stuck valve" in the valve body. Since there are 20+ "valves" AND the problem is intermittent, one does not know which "valve" to repair. In addition, GM vehicles are good about setting codes for mechanical valve body issues. There were no transmission related codes in the PCM but there were other electrical and ABS codes stored. The description of some of these codes indicate potential interference with the transmission operation. In short, if there were a clear indication on what needed to be repaired it would have been competed under the ATRA guidelines. ATRA protocol did not kick in in this case because there was no fault found in original transmission builders work. The offer was made to the customer to re-inspect the vehicle, at no cost to the customer, if the problem reoccurs.