Vintage Synth Repair

I have an Octave Cat (not SRM) with a few sliders that are very
resistant to movement.  
They function but not in a readily tweakbale way.  I've tried contact
cleaner to no avail.  Is 
there a special lubricant/cleaner for this type of problem?  The sliders do
not seem to be bent too 
badly as to create extra friction, although I believe there is some evident oxidation.  Also, 
the noise feature on the
synth generally works for 
up to twenty minutes after power-up, then disappears.  A bad
capacitor?  Lastly, I will 
soon attempt to replace the bushings (purchased from Archive Sound)
on the keyboard.  It 
seems pretty straightforward, but I would welcome any advice from
someone who has 
successfully replaced them.  Got some ProGold from Caig to clean the bus bars and j-
wires.  Thanks for any help!

Stephen