Desolder all 3 leads of the POT.
Unclip it from the metal housing.
You'll see 3 small posts in the corners of the POT. These keep it fixed in place while it's mounted to the metal housing.
Use an Xacto knife or razor blade and cut those 3 small posts off. Do NOT cut the clips off the sides, just the 3 small posts in the corners as those clips are needed to hold the POT on the the metal housing.
Now when you clip the POT back onto the housing, it will have a little bit of 'play' in it where you can rotate it left or right, before soldering it in place, that can be used to tweak it back so the center value matches what the thing was calibrated to. It may take a couple of tries to get it.
NOTE/WARNING: Go easy on the desoldering and soldering as to not tear up the pads for the POT leads, as the soldering is what will be holding the POT aligned in place since the posts have been removed.