Where should the level bubble be?

I don't use the bubble... Try this if you have an iPhone and in most cases 6.5 degrees is a good starting point.
https://itunes.apple.com/de/app/pinguy/id782973821

It tells you in the manual.

The first line is at 6 degrees, and each line after that is another .5 degrees. The second line is thicker than the others, because it indicates the recommended 6.5 degree pitch. In your photo, the bubble is right around the 7.5 degree mark.

Here's an excerpt from the TZ manual:

TRU-PITCH.PNG

When I tried to rely on memory in levelling my game (instead of figuring out where I'd boxed up the manual when I moved) I used the wrong end of the bubble. TZ is pretty brutal when its set to 11.5 degrees, as it turns out!

Hahaha ya think?

My JB says the same, 6.5 degrees. I have my WW set at 7.5, one must wonder if that's why the upper ramp is so dang hard to hit...

I love the line, "We DO NOT recommend a pitch of less than 6 degrees as this could lead to longer ball time and adverse earnings"

That seems to be the typical MO here lately. Who needs parts numbers when I can just ask everyone online?

My advice would be to ignore the factory bubble. They're often not correct. Like a wood frame house, the cabinets settle over time. Instead, go down to Sears and get their digital torpedo level. It's reasonably priced (~$30) and lets you quickly adjust pitch and level to within one tenth of a degree. Pitch should be adjusted with the level between the flippers. Once you set the pitch using the digital level, you can adjust your factory bubble to read correctly.

I see you own 11 games. With that many games, you really should have a good digital level. Not an app you have to calibrate, a real digital level.

I agree. The apps suck. Got a digital level after I moved into the new house. The basement has a slope so leveling games is a real pain in the ass. Digital level is great. Before that I used the wedge method with a normal torpedo level.