Thanks drbrain - this leaf adjustment seems to have addressed my issue. Because of the overly downward tilt, a ball would easily actuate Switch 53 when going up (backward) but when going down (building shot) the chute, there wasn't enough displacement of the leaf. Didn't take too much of a tweak to make it right. I did a handful of tests of the Oxygen Destroyer and it defuses every time now. Doesn't seem like this area would need adjustment in the future but if it does, I know where to tweak.
Quoted from drbrain:I just checked my leaf switch at 53 and it is very flat and straight. Yours looks a little bit bent down but not that much as there is pressure placed on the switch naturally from the gate. First, to adjust a leaf switch always use a leaf switch adjuster tool.
Here is a link to one - https://www.pinballlife.com/ultimate-leaf-adjuster-tool.html
Be careful when adjusting switches as a very little change can make a big difference. Also you would most likely want to adjust it further back than at the end, hard to say till you try but go slow. I would roll a ball through in both directions while in switch test and watch the motion of the switch and see if it closes the small plunger and it registers in the switch test. You can also move the gate manually and see what happens. Remember the ball may not move the gate as much as you do manually when it goes through and speed can play a factor sometimes.
Good luck and if anyone else wants to jump in please do as I wonder if it could be something else as well.
Turns out in my case I had TWO issues. The Switch 53 issue above that was not registering and not defusing the Oxygen Destroyer - but also the set screw that holds the pulley to the building ballscrew (in the lower mechanism) had backed out. The stepper motor would start, turn the belt and two pulleys, but since the driven pulley was not anchored to the shaft, the building would never move. Easy one to fix, just orient the pulley set screw to the flat on the end of the ballscrew and tighten.
So, back in action with Godzilla multiball and building movement and with Oxygen Destroyer too.
Now to play some pinball with all the features working!