Cleaning a scratchy volume control...

I use fader lube
http://www.amazon.com/Hosa-F5S-H6-CAIG-DeoxIT-Faderlube/dp/B00006LVF1/ref=sr_1_1?ie=UTF8&qid=145...

It works on carbon and plastic tracks, plus is safe on metal.  It is designed specifically "to lubricate faders on all audio mixers and treat oxidized fader components that are usually the cause of fader noise and audio leakage."

+1  Same stuff I use.

I guess I should open the unit up and look for an entry point to spray into the attenuator from the housing?  Or first just take of the knob and see if there is an access point along the shaft?  Thoughts?

Pot in my DAC is PCB mount.  It is small plastic square that have end cap with two diagonal screws.  I lift one corner with exacto blade and thru tiny gap I spray it inside.  This stuff is non-corrosive and non-conducting but I placed paper towels underneath to avoid big mess.
Spraying on the shaft holding it vertically and hoping it will soak in did not work (but it might work for you).  If you find any opening (many pots had slots near soldedring tabs) spray a lot of it inside.