Just curious... which switch did you get from O'Reilly?

Autozone's switch was made by Wells (ugh) according to their website.

I have never had a problem, so far, anyway, with any electrical part made by BWD. The low-line O'Reilly Master Pro part might be made by Wells too.

It sounds like the switch decks of the switch have not been assembled correctly, or their detent mechanism is off tolerance. All you're doing is pushing in your existing shaft into it till it seats, and plugging in the connector. It would seem hard to screw that up, so it's probably the switch.