2 Potentiometers changed reference points.

We have 2 potentiometers on our bot each of which started reading values around 300 and 450 larger than before. We have been using these for 3 months and they both did this at the same time on different parts of the bot. Any help is greatly appreciated.

Are they still reading changes fairly consistently, just with that shift from before? If so, it’s likely the potentiometers themselves rotated a little on the robot. Have to checked to make sure they’re held down really well?

Also, there is a little line on the potentiometer that shows what position it is currently rotated to.