I worked as a GM dealer tech for 26 years. Worked with more than a few that couldn't tie their shoes. Compile that with the fact that the factory expects diagnosis for little if any time paid to the tech. When we did a trans. GM would only pay to replace the faulty part. And only pay to go as deep as that part. So if you gutted the entire trans to clean it up, that was a free be. One of the last jobs I did was a spun bearing in a front drive Cobalt 4 cylinder. It spun a rod. Dropped everything out the bottom. Then pulled the engine out of the lowered cradle. Pulled the head, timing chain, balance chain to pull one piston. Pressed the rod off and new rod on. the original piston. Swapped the crank. Put it all back together. Recharged the AC. Aligned the front suspension. It paid 9.2 hrs.
Doug