Quoted from johnwartjr:A TZ adds another layer of complexity to resets, a Z connector between the driver board and CPU. Not expensive to replace, pretty easy to diagnose.
As John alluded to, TZ resets can be one of about a dozen possibilities.
The Z connector he referenced above was what I found to be the problem on mine. Eliminated it, and the game's never reset since.
Here's some recommended reading:
http://pinwiki.com/wiki/index.php?title=A_disciplined_process_to_eliminate_WPC_game_resets