Loose volume pot on '88 Spoiler

[clarkybass]

The volume pot on my Spoiler turns VERY freely as there is little friction or 'grab'. Generally this is not a problem as I have the volume on full (ie, pot turned to maximum) and if I need to cut the volume completely, I can use the 'pickup disengage' setting on the rotary switch. Occasionally though I do knock the pot while playing and it shifts the volume down all too easily, meaning that I have to scrabble quickly to turn the pot to max again.
 
I have no knowledge of the workings of pots so could anyone tell me if there is an easy fix for this or whether I need a replacement pot? How much are replacement Alembic pots as well, in case one of you guys knows?  
 
Thanks in advance, Clarky

[adriaan]

You could put a some sort of felt disk underneath the knob.

[bigredbass]

Are you sure the nut holding the pot in place (below the knob) is snug, and the knob too?
 
J o e y

[clarkybass]

I took off the knob after reading your suggestion, bigredbass, and then screwed it back in tightly via the two grub screws, which slightly improved matters. The nut underneath seemed tight. As said, slightly better but still doesn't have the same smooth but friction-generating turn of the tone pot, though.