As I didn't want to keep the servo powered when the tilt bracket isn't used I ran into a small problem. I would detach the servo after tilting the phone but sometimes the mechanical friction of the gears wasn't enough to hold the phone and the bracket in place and they would dip to the lowest position.
This can be helped a bit by waiting for a while before detaching the servo after rotating it, so that the gears aren't in motion anymore when the servo loses control.
But as the medium servo isn't really that powerful even this wasn't enough sometimes. The bracket would still dip. I thought about adding a counterweight on the other side as now all the weight was on the side of the phone. But I didn't really have anything with enough weight in a small package.
So another low-tech solution to this was to pull a rubber band from the top of the tilt bracket down to the robot chassis. It nicely balances the weight of the phone and the servo no longer rotates uncontrollably to the low position.