How to fix physics irregularities in 2D?

So, some background:
I’ve been making a little game in 2d where the player has to arrange bounce pads to manipulate a ball through obstacles and into a basket. Everything starts frozen, the player can arrange the pads, and when the player hits go everything unfreezes and the pads can’t be moved again until the player hits stop. When the player hits stop, everything is frozen again and each object is returned to the exact position/rotation they had when the player hit go.
The problem:
I made a level with some spinning wheels, and even without manually moving anything, the ball moves differently each run after falling out of the wheel. I don’t think the problem is that the wheels are being moved to incorrect positions. That’s what I thought at first, but even after completely rewriting the script that reset the positions the problem kept occurring. Below I’ve included screenshots of 2 consecutive runs in which nothing was manually moved. The orange dots represent the path of the ball. (I wanted to include a video, but I couldn’t get the file small enough.)

Does anyone know why this happens and how I can fix it?

In the end I actually figured out a solution to this myself. For anyone else experiencing similar problems, the solution was to update the Fixed Timestep to a smaller number (I reduced it from 0.02 to 0.01 and it fixed the problem). To change the Fixed Timestep, go to Project Setting → Time.