Reply to Fader cleaning

I was recently having some problems with the faders on my VCI 100 SE (volume and crossfade), I figured they just needed a nice cleaning so I took them out and let them soak in rubbing alcohol for a bit. They work fine now, but feel a little rough (mainly the volume faders). I figure they need some grease in them or something along the lines of that.

My question is, are they safe to use as is or do they need some lubricant to keep from getting worn out quickly?