[morzh]

What happens often times is this: closer to the beginning of the element, at its left side, where the volume is supposed to be low, there develops a rubb-through, so instead of the encountering the low resistance, the wiper encounters very high to infinite resistance, so no attenuation occurs and the volume gets loud. Then you rotate it a bit further and the wiper hits the conductive area, and so the voluime gets down, and then is rising as you keep moving the wiper towartds the right side (maximum volume).

Some people suggest rubbing the bald spot with the pensil. I think it is a palliative and won 't hold for long, but may work short-term. Especially if you treat it with Deoxit, that will luibriocate it and stop the wiper from taking that graphite of quickly.