Check the rollover switch on the right hand return ramp to make sure that is working. That triggers the diverter on you first attempt during a plunge. If you shoot too hard and bypass the skill shot, the diverter will send it back to the shooter lane to shoot again. If you shoot too hard again, the diverter will not activate and just drop the ball down by the flipper. The diverter does not activate at any other time during the game. Hope this helps.

The diverter also activated if you miss the ball lock skill shot for Multiball. You then get a 2 ball multiball where you have to shoot one ball in the lock and then you get 10-15 seconds to hit the left ramp and the diverter will open, sending the ball to the shooter lane for you to try the ball lock skill shot again. Pretty cool feature that they should have used a little more.
You rarely see this because the first time you get multiball the 1 and 2 holes are lit for the lock and it’s pretty hard to miss the first two, just make sure you plunge soft. I think the second multiball it’s always just the first hole that’s lit which is also hard to miss because again, just keep plunging soft. However the third multiball you get in a game usually has just the 2 or 3 hole lit to lock the ball which is much harder.