Thanks Kew, that video was great.
I definitely will give that a go and that should fix up that problem then thanks.
There could be more to it, but trying the contact cleaner is a pretty inexpensive proposition.
If the board the pot is mounted on won't come free as easily as the one in the video (I think pro audio gear is designed with consumer repair more in mind than home audio gear), you can often have good access just by removing the lid. Also, if I remember correctly, the last time I did this, there was a gap next to the shaft to spray cleaner in from the front. Flush it anyway you can and work the knob from time to time as you go.
