Mine had the same problem, downshifting into 2nd just wouldn't work. On teardown we found the blocker assembly was shot.
Psychology Today studies LS1Tech "please help!!" posters:
"The Dunning-Kruger effect describes a cognitive bias in which people perform poorly on a task, but lack the meta-cognitive capacity to properly evaluate their performance. As a result, such people remain unaware of their incompetence and accordingly fail to take any self-improvement measures that might rid them of their incompetence."