Lubricating clutch release bearing guide tube

[Sparkrite]

My clutch action is getting gradually more stiff and as I have isolated the cable as the source, I am thinking it's the clutch release bearing guide tube. I didn't pay enough attention to it last time I was in there but for now I would like to grease it a bit before I eventually have to pull out the gearbox.
Can this be done in situ without any dismantling.

[dakazman]

  I would suggest some wd-40 blown in by compressed air. A two man operation would be best to accomplish this.
Spray the cable and then actuate the cable while using compressed air around the sheathing. The one end inside car can also be sprayed but care must be taken to not destroy the carpeting. the corrosion is probably near either end.
 You could even disconnect it from the pedal and clutch arm and do a few pull test to see if it's the problem.
  Dakazman

[TurboFource]

Maybe a cable lubricant tool like for motorcycles?

[Sparkrite]

Sorry guys I left out 1 word which then makes my post misleading . It should have said " I have isolated the cable as  NOT  the source.
The clutch cable is all lubricated and working fine .

I need to Lubricate the clutch release bearing guide tube in situ as I think the small amount of grease  I had applied after doing my clutch disc has now gone and it's binding somewhat.