A new problem with my GZ Premium: sometimes the ball goes into the building, when lock is lit, and doesn't come out. I can sometimes reproduce this in switch test. The VUK Opto registers, but the VUK doesn't fire. It doesn't happen all the time in play, nor all the time in switch testing. I can't see the ball when it gets lost like that, but a ball search will cause the VUK to shoot it up, so I assume it's sitting in the little subway right on top of the VUK. I've removed that little subway, and there are no obstructions in it. If I physically lift up the front of the machine, the VUK will notice the ball, and shoot it up to the roof (if it's in switch test, where the tilt won't matter).
At first I thought maybe it was because I had the pitch at 7.5, so I lowered it to 6.8 (boy, does it seem floaty now!), but that made balls get lost more often. It is perfectly level side to side at the top of the playfield, and off by 0.1 at the bottom, as measured with a digital level (not a phone).
I've read this whole thread, and I don't remember seeing this issue. Couldn't find any mention of it by searching, either. Thanks for any help you can offer!