If it's a button type controller, the same method can be used as indicated in the linkd from bkay. It may not even be necessary to completely take apart the carbon disk container and clean the disks. It may be, and it is likely that the screw needs to be adjusted. A complete video on those is here:
https://www.youtube.com/watch?v=_gCy7gCn4po
If the screw is the only thing that needs adjusting, which to be frank, it may be, this is just a bit fiddly as you may have to adjust the nut holding it with a pair of pliers while you position the screw using a screwdriver. A bit of patience and about 5 to 10 minutes of fiddling is really all it takes.
Andytube has a series of videos on restoring a foot pedal, the adjustment video is here:
https://www.youtube.com/watch?v=Vz1iXW_Ghcs