chuckwurt Sorry for the late reply again, haven't had much time to work on the mech.
I've got the diverter working pretty well now. I'd say about 90% are locking appropriately. I've been using a digital caliper depth gauge to get the measurement from the end of the diverter to the back wall. The measurement that is working the best for me is .790 inches.
Also lubed the rubber washer pivot with zoom spout oil, even though the pivot wasn't rough. I'm not sure if it was the precise measurement or the lube that helped the most though.
We additionally installed the flipper coil fans from pinmonk and the kit was very nice with clear instructions. Well done vireland !
Now that the mech is working pretty well, the enjoyment factor of the game is definitely up! The game is finicky to set up for sure, but so worth it once it's all clicking. Thanks for all the tips, suggestions and advice!